SN250
Single-chip ZigBee 802.15.4 solution
Features
Integrated 2.4GHz, IEEE 802.15.4-compliant transceiver: Robust RX filtering allows co-existence with IEEE 802.11g and Bluetooth devices - 97 dBm RX sensitivity (1% PER, 20 byte packet) + 3dBm nominal output power Increased radio performance mode (boost mode) gives -98 dBm sensitivity and +5dBm transmit power Integrated VCO and loop filter Integrated IEEE 802.15.4 PHY and lower MAC with DMA Integrated hardware support for Packet Trace Interface for InSight Development Environment Provides integrated RC oscillator for low power operation Supports optional 32.768-kHz crystal oscillator for higher accuracy needs 16-bit XAP2b microprocessor
Integrated memory: 128 Kbytes of Flash 5 Kbytes of SRAM Configurable memory protection scheme Two sleep modes: Processor idle Deep sleep -1.0 A (1.5 A with optional 32.768-kHz oscillator enabled) Seventeen GPIO pins with alternate functions Two Serial Controllers with DMA SC1: I2C master, SPI master, UART SC2: I2C master, SPI master/slave Two 16-bit general-purpose timers; one 16-bit sleep timer Watchdog timer and power-on-reset circuitry Non-intrusive debug interface (SIF) Integrated AES encryption accelerator Integrated ADC module first-order, sigma-delta converter with 12-bit resolution Integrated 1.8V voltage regulator
October 2007
Rev 3
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Contents
SN250
Contents
1 2 3 4 5 General description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Order codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Pin assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Top-level functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.1 5.2 5.3 5.4 5.5 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Recommended operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Environmental characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 DC electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 RF electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.5.1 5.5.2 5.5.3 Receive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Transmit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Synthesizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
6
Functional description--system modules . . . . . . . . . . . . . . . . . . . . . . 20
6.1 Receive (RX) path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
6.1.1 6.1.2 RX baseband . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 RSSI and CCA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
6.2
Transmit (TX) path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
6.2.1 6.2.2 TX baseband . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 TX_ACTIVE signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
6.3 6.4 6.5 6.6
Integrated MAC module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Packet Trace Interface (PTI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 XAP2b microprocessor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Embedded memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
6.6.1 6.6.2 6.6.3 6.6.4 6.6.5 Flash memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Simulated EEPROM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Flash Information Area (FIA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 RAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
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6.7 6.8 6.9 6.10
Encryption accelerator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Reset detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Power-on-Reset (POR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Clock sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
6.10.1 6.10.2 6.10.3 High-frequency crystal oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Low-frequency oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Internal RC oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
6.11 6.12 6.13 6.14
Random number generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Watchdog timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Sleep timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Power management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
7
Functional description--application modules . . . . . . . . . . . . . . . . . . . 31
7.1 7.2 GPIO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
7.1.1 Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Serial controller SC1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
7.2.1 7.2.2 7.2.3 7.2.4 UART mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 SPI master mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 I2C master mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
7.3
Serial controller SC2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
7.3.1 7.3.2 7.3.3 SPI modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 I2C Master Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
7.4
General purpose timers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
7.4.1 7.4.2 7.4.3 7.4.4 7.4.5 7.4.6 Clock sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 Timer functionality (counting) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 Timer functionality (output compare) . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 Timer functionality (input capture) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 Timer interrupt sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
7.5 7.6
ADC module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
7.5.1 Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
Event manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
7.6.1 Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
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Contents
SN250
7.7
Integrated voltage regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
8 9 10 11 12 13 14
SIF module programming and debug interface . . . . . . . . . . . . . . . . . 117 Typical application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 Mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 Register address table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 Abbreviations and acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
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SN250
General description
1
General description
The SN250 is a single-chip solution that integrates a 2.4GHz, IEEE 802.15.4-compliant transceiver with a 16-bit XAP2b microprocessor. It contains integrated Flash and RAM memory and peripherals of use to designers of ZigBee-based applications. The transceiver utilizes an efficient architecture that exceeds the dynamic range requirements imposed by the IEEE 802.15.4-2003 standard by over 15dB. The integrated receive channel filtering allows for co-existence with other communication standards in the 2.4GHz spectrum such as IEEE 802.11g and Bluetooth. The integrated regulator, VCO, loop filter, and power amplifier keep the external component count low. An optional high performance radio mode (boost mode) is software selectable to boost dynamic range by a further 3dB. The XAP2b microprocessor is a power-optimized core integrated in the SN250. It supports two different modes of operation--System Mode and Application Mode. The ZNet stack runs in System Mode with full access to all areas of the chip. Application code runs in Application Mode with limited access to the SN250 resources; this allows for the scheduling of events by the application developer while preventing modification of restricted areas of memory and registers. This architecture results in increased stability and reliability of deployed solutions. The SN250 has 128KB of embedded Flash memory and 5KB of integrated RAM for data and program storage. The SN250 software stack employs an effective wear-leveling algorithm in order to optimize the lifetime of the embedded Flash. To maintain the strict timing requirements imposed by ZigBee and the IEEE 802.15.4-2003 standard, the SN250 integrates a number of MAC functions into the hardware. The MAC hardware handles automatic ACK transmission and reception, automatic backoff delay, and clear channel assessment for transmission, as well as automatic filtering of received packets. In addition, the SN250 allows for true MAC level debugging by integrating the Packet Trace Interface. To support user-defined applications, a number of peripherals such as GPIO, UART, SPI, I2C, ADC, and general-purpose timers are integrated. Also, an integrated voltage regulator, power-on-reset circuitry, sleep timer, and low-power sleep modes are available. The deep sleep mode draws less than 1A, allowing products to achieve long battery life. Finally, the SN250 utilizes the non-intrusive SIF module for powerful software debugging and programming of the XAP2b microcontroller. Target applications for the SN250 include:
Building automation and control Home automation and control Home entertainment control Asset tracking
The SN250 is purchased with ZNet, a ZigBee-compliant software stack developed by Ember Corporation, providing a ZigBee profile-ready, platform-compliant solution.This technical datasheet details the SN250 features available to customers using it with the ZNet stack.
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Order codes
SN250
2
Order codes
Part Number SN250Q SN250QT Temperature Range -40 to +85C -40 to +85C Package QFN48 QFN48 Packing Tray Tape & Reel Marking SN250 SN250
3
Pin assignment
Figure 1. SN250 pin assignment
Refer to Table 17 and Table 18 for selecting alternate pin functions.
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SN250 Table 1.
Pin # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
Pin assignment Pin descriptions
Signal VDD_24MHZ VDD_VCO RF_P RF_N VDD_RF RF_TX_ALT_P RF_TX_ALT_N VDD_IF BIAS_R VDD_PADSA TX_ACTIVE VDD_PADSA nRESET OSC32B OSC32A VREG_OUT VDD_PADS VDD_CORE GPIO11 nCTS Direction Power Power I/O I/O Power O O Power I Power O Power I I/O I/O Power Power Power I/O I Description 1.8V high-frequency oscillator supply 1.8V VCO supply Differential (with RF_N) receiver input/transmitter output Differential (with RF_P) receiver input/transmitter output 1.8V RF supply (LNA and PA) Differential (with RF_TX_ALT_N) transmitter output (optional) Differential (with RF_TX_ALT_P) transmitter output (optional) 1.8V IF supply (mixers and filters) Bias setting resistor Analog pad supply (1.8V) Logic-level control for external RX/TX switch Analog pad supply (1.8V) Active low chip reset (internal pull-up) 32.768kHz crystal oscillator or left open when using external clock on OSC32A 32.768kHz crystal oscillator or digital clock input Regulator output (1.8V) Pads supply (2.13.6V) 1.8V digital core supply Digital I/O (enable GPIO11 with GPIO_CFG[7:4]) UART CTS handshake of Serial Controller SC1 (enable SC1-4A with GPIO_CFG[7:4], select UART with SC1_MODE) SPI master clock of Serial Controller SC1 (enable SC1-3M with GPIO_CFG[7:4], select SPI with SC1_MODE, enable master with SC1_SPICFG[4]) Capture Input A of Timer 2 (enable CAP2-0 with GPIO_CFG[7:4]) Digital I/O (enable GPIO12 with GPIO_CFG[7:4]) UART RTS handshake of Serial Controller SC1 (enable SC1-4A with GPIO_CFG[7:4], select UART with SC1_MODE) Capture Input B for Timer 2 (enable CAP2-0 with GPIO_CFG[7:4])
19 MCLK O
TMR2IA.1 GPIO12 20 nRTS TMR2IB.1
I I/O O I
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Pin assignment Table 1.
Pin #
SN250
Pin descriptions (continued)
Signal GPIO0 Direction I/O Description Digital I/O (enable GPIO0 with GPIO_CFG[7:4]) SPI master data out of Serial Controller SC2 (enable SC2-3M with GPIO_CFG[7:4], select SPI with SC2_MODE, enable master with SC2_SPICFG[4]) SPI slave data in of Serial Controller SC2 (enable SC2-4S with GPIO_CFG[7:4], select SPI with SC2_MODE, enable slave with SC2_SPICFG[4]) Capture Input A of Timer 1 (enable CAP1-0 with GPIO_CFG[7:4]) Digital I/O (enable GPIO1 with GPIO_CFG[7:4]) SPI master data in of Serial Controller SC2 (enable SC2-3M with GPIO_CFG[7:4], select SPI with SC2_MODE, enable master with SC2_SPICFG[4]) SPI slave data out of Serial Controller SC2 (enable SC2-4S with GPIO_CFG[7:4], select SPI with SC2_MODE, enable slave with SC2_SPICFG[4]) I2C data of Serial Controller SC2 (enable SC2-2 with GPIO_CFG[7:4], select I2C with SC2_MODE) Capture Input A of Timer 2 (enable CAP2-1 with GPIO_CFG[7:4]) Pads supply (2.13.6V) Digital I/O (enable GPIO2 with GPIO_CFG[7:4]) SPI master clock of Serial Controller SC2 (enable SC2-3M with GPIO_CFG[7:4], select SPI with SC2_MODE, enable master with SC2_SPICFG[4]) SPI slave clock of Serial Controller SC2 (enable SC2-4S with GPIO_CFG[7:4], select SPI with SC2_MODE, enable slave with SC2_SPICFG[4]) I2C clock of Serial Controller SC2 (enable SC2-2 with GPIO_CFG[7:4], select I2C with SC2_MODE) Capture Input B of Timer 2 (enable CAP2-1 with GPIO_CFG[7:4])
MOSI 21 MOSI
O
I
TMR1IA.1 GPIO1
I I/O
MISO
I
22
MISO
O
SDA TMR2IA.2 23 VDD_PADS GPIO2
I/O I Power I/O
MSCLK
O
24
MSCLK
I
nSSEL TMR2IB.2
I/O I
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SN250 Table 1.
Pin #
Pin assignment Pin descriptions (continued)
Signal GPIO3 Direction I/O Description Digital I/O (enable GPIO3 with GPIO_CFG[7:4]) SPI slave select of Serial Controller SC2 (enable SC2-4S with GPIO_CFG[7:4], select SPI with SC2_MODE, enable slave with SC2_SPICFG[4]) Capture Input B of Timer 1 (enable CAP1-0 with GPIO_CFG[7:4]) Digital I/O (enable GPIO4 with GPIO_CFG[12] and GPIO_CFG[8]) ADC Input 0 (enable ADC0 with GPIO_CFG[12] and GPIO_CFG[8]) Frame signal of Packet Trace Interface (PTI) (enable PTI with GPIO_CFG[12]) Digital I/O (enable GPIO5 with GPIO_CFG[12] and GPIO_CFG[9]) ADC Input 1 (enable ADC1 with GPIO_CFG[12] and GPIO_CFG[9]) Data signal of Packet Trace Interface (PTI) (enable PTI with GPIO_CFG[12]) Pads supply (2.13.6V) Digital I/O (enable GPIO6 with GPIO_CFG[10]) ADC Input 2 (enable ADC2 with GPIO_CFG[10]) External clock input of Timer 2 External enable mask of Timer 1 Digital I/O (enable GPIO7 with GPIO_CFG[13] and GPIO_CFG[11]) ADC Input 3 (enable ADC3 with GPIO_CFG[13] and GPIO_CFG[11]) External regulator open collector output (enable REG_EN with GPIO_CFG[13]) Digital I/O (enable GPIO8 with GPIO_CFG[14]) ADC reference output (enable VREF_OUT with GPIO_CFG[14]) External clock input of Timer 1 External enable mask of Timer 2 External interrupt source A
25
nSSEL
I
TMR1IB.1 GPIO4 26 ADC0 PTI_EN GPIO5 27 ADC1 PTI_DATA 28 VDD_PADS GPIO6 ADC2 TMR2CLK TMR1ENMSK GPIO7 30 ADC3 REG_EN GPIO8 VREF_OUT 31 TMR1CLK TMR2ENMSK IRQA
I I/O Analog O I/O Analog O Power I/O Analog I I I/O Analog O I/O Analog I I I
29
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Pin assignment Table 1.
Pin #
SN250
Pin descriptions (continued)
Signal GPIO9 Direction I/O Description Digital I/O (enable GPIO9 with GPIO_CFG[7:4]) UART transmit data of Serial Controller SC1 (enable SC1-4A or SC1-2 with GPIO_CFG[7:4], select UART with
SC1_MODE)
TXD
O
32
MO
O
SPI master data out of Serial Controller SC1 (enable SC1-3M with GPIO_CFG[7:4], select SPI with SC1_MODE, enable master with SC1_SPICFG[4]) I2C data of Serial Controller SC1 (enable SC1-2 with GPIO_CFG[7:4], select I2C with SC1_MODE) Capture Input A of Timer 1 (enable CAP1-1 or CAP1-1h with GPIO_CFG[7:4]) Digital I/O (enable GPIO10 with GPIO_CFG[7:4]) UART receive data of Serial Controller SC1 (enable SC1-4A or SC1-2 with GPIO_CFG[7:4], select UART with
SC1_MODE)
MSDA TMR1IA.2 GPIO10
I/O I I/O
RXD
I
33
MI
I
SPI master data in of Serial Controller SC1 (enable SC1-3M with GPIO_CFG[7:4], select SPI with SC1_MODE, enable master with SC1_SPICFG[4]) I2C clock of Serial Controller SC1 (enable SC1-2 with GPIO_CFG[7:4], select I2C with SC1_MODE) Capture Input B of Timer 2 (enable CAP1-1 with GPIO_CFG[7:4]) Serial interface, clock (internal pull-down) Serial interface, master in/slave out Serial interface, master out/slave in Serial interface, load strobe (open-collector with internal pull-up) Ground supply 1.8V Flash memory supply Digital I/O (enable GPIO16 with GPIO_CFG[3]) Waveform Output B of Timer 1 (enable TMR1OB with GPIO_CFG[3]) Capture Input B of Timer 2 (enable CAP2-2 with GPIO_CFG[7:4]) External interrupt source D
MSCL TMR1IB.2 34 35 36 37 38 39 SIF_CLK SIF_MISO SIF_MOSI nSIF_LOADB GND VDD_FLASH GPIO16 TMR1OB 40 TMR2IB.3 IRQD
I/O I I O I I/O Power Power I/O O I I
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SN250 Table 1.
Pin #
Pin assignment Pin descriptions (continued)
Signal GPIO15 TMR1OA Direction I/O O I I I/O O I I I/O O I Power Power Power I/O I/O Ground Description Digital I/O (enable GPIO15 with GPIO_CFG[2]) Waveform Output A of Timer 1 (enable TMR1OA with GPIO_CFG[2]) Capture Input A of Timer 2 (enable CAP2-2 with GPIO_CFG[7:4]) External interrupt source C Digital I/O (enable GPIO14 with GPIO_CFG[1]) Waveform Output B of Timer 2 (enable TMR2OB with GPIO_CFG[1]) Capture Input B of Timer 1 (enable CAP1-2 with GPIO_CFG[7:4]) External interrupt source B Digital I/O (enable GPIO13 with GPIO_CFG[0]) Waveform Output A of Timer 2 (enable TMR2OA with GPIO_CFG[0]) Capture Input A of Timer 1 (enable CAP1-2 or CAP1-2h with GPIO_CFG[7:4]) 1.8V digital core supply 1.8V prescaler supply 1.8V synthesizer supply 24MHz crystal oscillator or left open when using external clock input on OSCA 24MHz crystal oscillator or external clock input Ground supply pad in the bottom center of the package forms Pin 49 (see the SN250 Reference Design for PCB considerations)
41 TMR2IA.3 IRQC GPIO14 TMR2OB 42 TMR1IB.3 IRQB GPIO13 43 TMR2OA TMR1IA.3 44 45 46 47 48 49 VDD_CORE VDD_PRE VDD_SYNTH OSCB OSCA GND
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Top-level functional description
SN 2 5 0
4
Top-level functional description
Figure 2 shows a detailed block diagram of the SN250.
Figure 2.
SN250 block diagram
The radio receiver is a low-IF, super-heterodyne receiver. It utilizes differential signal paths to minimize noise interference, and its architecture has been chosen to optimize coexistence with other devices within the 2.4GHz band (namely, IEEE 802.11g and Bluetooth). After amplification and mixing, the signal is filtered and combined prior to being sampled by an ADC. The digital receiver implements a coherent demodulator to generate a chip stream for the hardware-based MAC. In addition, the digital receiver contains the analog radio calibration routines and control of the gain within the receiver path. The radio transmitter utilizes an efficient architecture in which the data stream directly modulates the VCO. An integrated PA boosts the output power. The calibration of the TX path as well as the output power is controlled by digital logic. If the SN250 is to be used with an external PA, the TX_ACTIVE signal should be used to control the timing of the external switching logic. The integrated 4.8 GHz VCO and loop filter minimize off-chip circuitry. Only a 24MHz crystal with its loading capacitors is required to properly establish the PLL reference signal. The MAC interfaces the data memory to the RX and TX baseband modules. The MAC provides hardware-based IEEE 802.15.4 packet-level filtering. It supplies an accurate symbol time base that minimizes the synchronization effort of the software stack and meets
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SN250
Top-level functional description the protocol timing requirements. In addition, it provides timer and synchronization assistance for the IEEE 802.15.4 CSMA-CA algorithm. The SN250 integrates hardware support for a Packet Trace module, which allows robust packet-based debug. This element is a critical component of InSight Desktop, the software IDE developed by Ember Corporation, providing advanced network debug capability when coupled with the InSight Adapter. The SN250 integrates a 16-bit XAP2b microprocessor developed by Cambridge Consultants Ltd. This power-efficient, industry-proven core provides the appropriate level of processing power to meet the needs of ZigBee applications. In addition, 128KB of Flash and 5KB of SRAM comprise the program and data memory elements, respectively. The SN250 employs a configurable memory protection scheme usually found on larger microcontrollers. In addition, the SIF module provides a non-intrusive programming and debug interface allowing for real-time application debugging. The SN250 contains 17 GPIO pins shared with other peripheral (or alternate) functions. Flexible routing within the SN250 lets external devices utilize the alternate functions on a variety of different GPIOs. The integrated Serial Controller SC1 can be configured for SPI (master-only), I2C (master-only), or UART functionality, and the Serial Controller SC2 can be configured for SPI (master or slave) or I2C (master-only) operation. The SN250 has an ADC integrated which can sample analog signals from four GPIO pins single-ended or differentially. In addition, the unregulated voltage supply VDD_PADS, regulated supply VDD_PADSA, voltage reference VREF, and GND can be sampled. The integrated voltage reference VREF for the ADC can be made available to external circuitry. The integrated voltage regulator generates a regulated 1.8V reference voltage from an unregulated supply voltage. This voltage is decoupled and routed externally to supply the 1.8V to the core logic. In addition, an integrated POR module allows for the proper cold start of the SN250. The SN250 contains one high-frequency (24MHz) crystal oscillator and, for low-power operation, a second low-frequency oscillator (either an internal 10kHz RC oscillator or an external 32.768kHz crystal oscillator). The SN250 contains two power domains. The always-powered High Voltage Supply is used for powering the GPIO pads and critical chip functions. The rest of the chip is powered by a regulated Low Voltage Supply which can be disabled during deep sleep to reduce the power consumption.
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Electrical characteristics
SN 2 5 0
5
5.1
Electrical characteristics
Absolute maximum ratings
Table 2 lists the absolute maximum ratings for the SN250. Table 2.
Parameter Regulator voltage (VDD_PADS) Core voltage (VDD_24MHz, VDD_VCO, VDD_RF, VDD_IF, VDD_PADSA, VDD_FLASH, VDD_PRE, VDD_SYNTH, VDD_CORE) Voltage on RF_P,N; RF_TX_ALT_P,N Voltage on any GPIO[16:0], SIF_CLK, SIF_MISO, SIF_MOSI, SIF_LOADB, OSC32A, OSC32B, RSTB, VREG_OUT Voltage on TX_ACTIVE, BIAS_R, OSCA, OSCB Storage temperature
Absolute maximum ratings
Test Conditions Min. - 0.3 - 0.3 - 0.3 - 0.3 - 0.3 - 40 Max. 3.6 Unit V
2.0
V
3.6 VDD_PADS + 0.3 VDD_CORE + 0.3 + 140
V V
V C
5.2
Recommended operating conditions
Table 3 lists the rated operating conditions of the SN250. Table 3.
Parameter Regulator input voltage (VDD_PADS) Core input voltage (VDD_24MHZ, VDD_VCO, VDD_RF, VDD_IF, VDD_PADSA, VDD_FLASH, VDD_PRE, VDD_SYNTH, VDD_CORE) Temperature range
.
Operating conditions
Test Conditions Min. 2.1 Typ. Max. 3.6 Unit V
1.7
1.8
1.9
V
-40
+ 85
C
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SN250
Electrical characteristics
5.3
Environmental characteristics
Table 4 lists the environmental characteristics of the SN250. Table 4.
Parameter ESD (human body model) ESD (charged device model) ESD (charged device model) Moisture Sensitivity Level (MSL1)
Environmental characteristics
Test Conditions On any Pin Non-RF Pins RF Pins Min. -2 - 400 - 225 TBD Typ. Max. +2 + 400 + 225 Unit kV V V
5.4
DC electrical characteristics
Table 5 lists the DC electrical characteristics of the SN250. Table 5.
Parameter Regulator input voltage (VDD_PADS) Power supply range (VDD_CORE) Deep Sleep Current Quiescent current, including internal RC oscillator Quiescent current, including 32.768kHz oscillator RX Current Radio receiver, MAC, and baseband (boost mode) Radio receiver, MAC, and baseband CPU, RAM, and Flash memory Total RX current ( = IRadio receiver, MAC and baseband, CPU + IRAM, and Flash memory) TX Current Radio transmitter, MAC, and baseband (boost mode) At max. TX power (+ 5dBm typical) 33.0 mA At 25 C and 1.8V core At 25 C, VDD_PADS=3.0V 29.0 27.0 8.5 mA mA mA At 25 C. At 25 C. 1.0 1.5 A A Regulator output or external input
DC characteristics
Test Conditions Min. 2.1 1.7 1.8 Typ. Max. 3.6 1.9 Unit V V
35.5
mA
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Electrical characteristics Table 5.
Parameter
SN 2 5 0
DC characteristics (continued)
Test Conditions At max. TX power (+ 3dBm typical) Min. Typ. 27.0 24.3 19.5 8.5 Max. Unit mA mA mA mA
Radio transmitter, MAC, and baseband
At 0 dBm typical At min. TX power (- 32dBm typical)
CPU, RAM, and Flash memory
At 25 C, VDD_PADS = 3.0V
Total TX current ( = IRadio transmitter, MAC and baseband, At 25 C and 1.8V core; max. power out CPU + IRAM, and Flash memory )
35.5
mA
Table 6 contains the digital I/O specifications for the SN250. The digital I/O power (named VDD_PADS) comes from three dedicated pins (Pins 17, 23, and 28). The voltage applied to these pins sets the I/O voltage. Table 6.
Parameter Voltage supply Input voltage for logic 0 Input voltage for logic 1 Input current for logic 0 Input current for logic 1 Input pull-up resistor value Input pull-down resistor value Output voltage for logic 0 Output voltage for logic 1 Output source current (standard current pad) Output sink current (standard current pad)
Digital I/O specifications
Name VDD_PADS VIL VIH IIL IIH RIPU RIPD VOL VOH IOHS IOLS 0 0.82 x VDD_PADS 30 30 0.18 x VDD_PADS VDD_PADS 4 4 8 8 40 0.2 0.8 VDD_PADS Min. 2.1 0 0.8 x VDD_PADS Typ. Max. 3.6 0.2 x VDD_PADS VDD_PADS - 0.5 0.5 Unit V V V A A k k V V mA mA mA mA mA V
Output source current (high IOHH current pad: GPIO[16:13]) Output sink current (high current pad: GPIO[16:13]) IOLH
Total output current (for I/O IO H + IO L Pads) Input voltage threshold for OSC32A
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SN250 Table 6.
Parameter Input voltage threshold for OSCA Output voltage level (TX_ACTIVE) Output source current (TX_ACTIVE)
Electrical characteristics Digital I/O specifications
Name Min. 0.2 0.18 VDD_CORE Typ. Max. 0.8 VDD_CORE 0.82 VDD_CORE 1 V mA Unit
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Electrical characteristics
SN 2 5 0
5.5
5.5.1
RF electrical characteristics
Receive
Table 7 lists the key parameters of the integrated IEEE 802.15.4 receiver on the SN250. Table 7.
Parameter Frequency range Sensitivity (boost mode) Sensitivity High-side adjacent channel rejection Low-side adjacent channel rejection 2nd high-side adjacent channel rejection 2nd low-side adjacent channel rejection Channel rejection for all other channels 802.11g rejection centered at + 12MHz or - 13MHz Maximum input signal level for correct operation (low gain) Image suppression Co-channel rejection Relative frequency error (2x40 ppm required by IEEE 802.15.4) Relative timing error (2x40 ppm required by IEEE 802.15.4) Linear RSSI range IEEE 802.15.4 signal at - 82dBm - 120 1% PER, 20byte packet defined by IEEE 802.15.4 1% PER, 20byte packet defined by IEEE 802.15.4 IEEE 802.15.4 signal at - 82dBm IEEE 802.15.4 signal at - 82dBm IEEE 802.15.4 signal at - 82dBm IEEE 802.15.4 signal at - 82dBm IEEE 802.15.4 signal at - 82dBm IEEE 802.15.4 signal at - 82dBm 0 30 -6
.
Receive characteristics
Test Conditions Min. 2400 - 93 - 92 - 98 - 97 35 35 40 40 40 40 Typ. Max. 2500 Unit MHz dBm dBm dB dB dB dB dB dB dBm dB dBc
+ 120
ppm
- 120 40
+ 120
ppm dB
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SN250
Electrical characteristics
5.5.2
Transmit
Table 8 lists the key parameters of the integrated IEEE 802.15.4 transmitter on the SN250. Table 8.
Parameter Maximum output power (boost mode) Maximum output power Minimum output power Error vector magnitude Carrier frequency error Load impedance PSD mask relative PSD mask absolute 3.5MHz away 3.5MHz away - 20 - 30
Transmit characteristics
Test Conditions At highest power setting At highest power setting At lowest power setting As defined by IEEE 802.15.4, which sets a 35% maximum - 40 200 0 Min. Typ. 5 3 - 32 15 25 + 40 Max. Unit dBm dBm dBm % ppm dB dBm
5.5.3
Synthesizer
Table 9 lists the key parameters of the integrated synthesizer on the SN250. Table 9.
Parameter Frequency range Frequency resolution Lock time From off, with correct VCO DAC setting Channel change or RX/TX turnaround (IEEE 802.15.4 defines 192s turnaround time) - 71 - 91 - 103 - 111
Synthesizer characteristics
Test Conditions Min. 2400 11.7 100 Typ. Max. 2500 Unit MHz kHz s s dBc/Hz dBc/Hz dBc/Hz dBc/Hz
Relock time Phase noise at 100kHz Phase noise at 1MHz Phase noise at 4MHz Phase noise at 10MHz
100
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Functional description--system modules
SN250
6
Functional description--system modules
The SN250 contains a dual-thread mode of operation--System Mode and Application Mode--to guarantee microcontroller bandwidth to the application developer and protect the developer from errant software access. During System Mode, all areas including the RF Transceiver, MAC, Packet Trace Interface, Sleep Timer, Power Management Module, Watchdog Timer, and Power on Reset Module are accessible. Since the SN250 comes with a license to ZNet, a ZigBee-compliant software stack developed by Ember Corporation, these areas are not available to the application developer in Application Mode. The following brief description of these modules provides the necessary background on the operation of the SN250. For more information, please contact your nearest STMicroelectronics sales office.
6.1
Receive (RX) path
The SN250 RX path spans the analog and digital domains. The RX architecture is based on a low-IF, super-heterodyne receiver. It utilizes differential signal paths to minimize noise interference. The input RF signal is mixed down to the IF frequency of 4MHz by I and Q mixers. The output of the mixers is filtered and combined prior to being sampled by a 12Msps ADC. The RX filtering within the RX path has been designed to optimize the coexistence of the SN250 with other 2.4GHz transceivers, such as the IEEE 802.11g and Bluetooth.
6.1.1
RX baseband
The SN250 RX baseband (within the digital domain) implements a coherent demodulator for optimal performance. The baseband demodulates the O-QPSK signal at the chip level and synchronizes with the IEEE 802.15.4-2003 preamble. Once a packet preamble is detected, it de-spreads the demodulated data into 4-bit symbols. These symbols are buffered and passed to the hardware-based MAC module for filtering. In addition, the RX baseband provides the calibration and control interface to the analog RX modules, including the LNA, RX Baseband Filter, and modulation modules. The ZNet software includes calibration algorithms which use this interface to reduce the effects of process and temperature variation.
6.1.2
RSSI and CCA
The SN250 calculates the RSSI over an 8-symbol period as well as at the end of a received packet. It utilizes the RX gain settings and the output level of the ADC within its algorithm. The SN250 RX baseband provides support for the IEEE 802.15.4-2003 required CCA methods summarized in Table 10. Modes 1, 2, and 3 are defined by the 802.15.4-2003 standard; Mode 0 is a proprietary mode.
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SN250 Table 10.
CCA Mode 0 1 2 3
Functional description--system modules CCA Mode Behavior
Mode Behavior Clear channel reports busy medium if either carrier sense OR RSSI exceeds their thresholds. Clear channel reports busy medium if RSSI exceeds its threshold. Clear channel reports busy medium if carrier sense exceeds its threshold. Clear channel reports busy medium if both RSSI AND carrier sense exceed their thresholds.
6.2
Transmit (TX) path
The SN250 transmitter utilizes both analog circuitry and digital logic to produce the O-QPSK modulated signal. The area-efficient TX architecture directly modulates the spread symbols prior to transmission. The differential signal paths increase noise immunity and provide a common interface for the external balun.
6.2.1
TX baseband
The SN250 TX baseband (within the digital domain) performs the spreading of the 4-bit symbol into its IEEE 802.15.4-2003-defined 32-chip I and Q sequence. In addition, it provides the interface for software to perform the calibration of the TX module in order to reduce process, temperature, and voltage variations.
6.2.2
TX_ACTIVE signal
Even though the SN250 provides an output power suitable for most ZigBee applications, some applications will require an external power amplifier (PA). Due to the timing requirements of IEEE 802.15.4-2003, the SN250 provides a signal, TX_ACTIVE, to be used for external PA power management and RF Switching logic. When in TX, the TX Baseband drives TX_ACTIVE high (as described in Table 6). When in RX, the TX_ACTIVE signal is low. If an external PA is not required, then the TX_ACTIVE signal should be connected to GND through a 100 k resistor, as shown in the application circuit in Figure 16.
6.3
Integrated MAC module
The SN250 integrates critical portions of the IEEE 802.15.4-2003 MAC requirements in hardware. This allows the microcontroller to provide greater bandwidth to application and network operations. In addition, the hardware acts as a first-line filter for non-intended packets. The SN250 MAC utilizes a DMA interface to RAM memory to further reduce the overall microcontroller interaction when transmitting or receiving packets. When a packet is ready for transmission, the software configures the TX MAC DMA by indicating the packet buffer RAM location. The MAC waits for the backoff period, then transitions the baseband to TX mode and performs channel assessment. When the channel is clear, the MAC reads data from the RAM buffer, calculates the CRC, and provides 4-bit symbols to the baseband. When the final byte has been read and sent to the baseband, the CRC remainder is read and transmitted.
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Functional description--system modules
SN250
The MAC resides in RX mode most of the time, and different format and address filters keep non-intended packets from using excessive RAM buffers, as well as preventing the CPU from being interrupted. When the reception of a packet begins, the MAC reads 4-bit symbols from the baseband and calculates the CRC. It assembles the received data for storage in a RAM buffer. A RX MAC DMA provides direct access to the RAM memory. Once the packet has been received, additional data is appended to the end of the packet in the RAM buffer space. The appended data provides statistical information on the packet for the software stack. The primary features of the MAC are:
CRC generation, appending, and checking Hardware timers and interrupts to achieve the MAC symbol timing Automatic preamble, and SFD pre-pended to a TX packet Address recognition and packet filtering on received packets Automatic acknowledgement transmission Automatic transmission of packets from memory Automatic transmission after backoff time if channel is clear (CCA) Automatic acknowledgement checking Time stamping of received and transmitted messages Attaching packet information to received packets (LQI, RSSI, gain, time stamp, and packet status) IEEE 802.15.4 timing and slotted/unslotted timing
6.4
Packet Trace Interface (PTI)
The SN250 integrates a true PHY-level PTI for effective network-level debugging. This twosignal interface monitors all the PHY TX and RX packets (in a non-intrusive manner) between the MAC and baseband modules. It is an asynchronous 500 Kbps interface and cannot be used to inject packets into the PHY/MAC interface. The two signals from the SN250 are the frame signal (PTI_EN) and the data signal (PTI_DATA). The PTI is supported by InSight Desktop.
6.5
XAP2b microprocessor
The SN250 integrates the XAP2b microprocessor developed by Cambridge Consultants Ltd., making it a true system-on-a-chip solution. The XAP2b is a 16-bit Harvard architecture processor with separate program and data address spaces. The word width is 16 bits for both the program and data sides. Data-side addresses are always specified in bytes, though they can be accessed as either bytes or words, while program-side addresses are always specified and accessed as words. The data-side address bus is effectively 15 bits wide, allowing for an address space of 32KB; the program-side address bus is 16 bits wide, addressing 64k words. The standard XAP2 microprocessor and accompanying software tools have been enhanced to create the XAP2b microprocessor used in the SN250. The XAP2b adds data-side byte addressing support to the XAP2 by utilizing the 15th bit of the data-side address bus to indicate byte or word accesses. This allows for more productive usage of RAM, optimized code, and a more familiar architecture for customers when compared to the standard XAP2.
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SN250
Functional description--system modules The XAP2b clock speed is 12MHz. When used with the ZNet stack, code is loaded into Flash memory over the air or by a serial link using a built-in bootloader in a reserved area of the Flash. Alternatively, code may be loaded via the SIF interface with the assistance of RAM-based utility routines also loaded via SIF. The XAP2b in the SN250 has also been enhanced to support two separate protection levels. The ZNet stack runs in System Mode, which allows full, unrestricted access to all areas of the chip, while application code runs in Application Mode. When running in Application Mode, writing to certain areas of memory and registers is restricted to prevent common software bugs from interfering with the operation of the ZNet stack. These errant writes are captured and details are reported to the developer to assist in tracking down and fixing these issues.
6.6
Embedded memory
As shown in Figure 3, the program side of the address space contains mappings to both integrated Flash and RAM blocks. Figure 3. Program address space
The data side of the address space contains mappings to the same Flash and RAM blocks, as well as registers and a separate Flash information area, as shown in Figure 4.
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Functional description--system modules Figure 4. Data address space
SN250
6.6.1
Flash memory
The SN250 integrates 128KB of Flash memory. The Flash cell has been qualified for a data retention time of >100 years at room temperature. Each Flash page size is 1024 bytes and is rated to have a guaranteed 1,000 write/erase cycles. The Flash memory has mappings to both the program and data side address spaces. On the program side, the first 112KB of the Flash memory are mapped to the corresponding first 56k word addresses to allow for code storage, as shown in Figure 3. On the program side, the Flash is always read as whole words. On the data side, the Flash memory is divided into eight 16KB sections, which can be separately mapped into a Flash window for the storage of constant data and the Simulated EEPROM. As shown in Figure 4, the Flash window corresponds to the first 16KB of the data-side address space. On the data side, the Flash may be read as bytes, but can only be written to one word at a time using utility routines in the ZNet stack and HAL.
6.6.2
Simulated EEPROM
The ZNet stack reserves a section of Flash memory to provide Simulated EEPROM storage area for stack and customer tokens. Therefore, the SN250 utilizes 8KB of upper Flash storage. This section of Flash is only accessible when mapped to the Flash window in the data-side address space. Because the Flash cells are qualified for up to 1,000 write cycles,
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SN250
Functional description--system modules the Simulated EEPROM implements an effective wear-leveling algorithm which effectively extends the number of write cycles for individual tokens.
6.6.3
Flash Information Area (FIA)
The SN250 also includes a separate 1024-byte FIA that can be used for storage of data during manufacturing, including serial numbers and calibration values. This area is mapped to the data side of the address space, starting at address 0x5000. While this area can be read as individual bytes, it can only be written to one word at a time, and may only be erased as a whole. Programming of this special Flash page can only be enabled using the SIF interface to prevent accidental corruption or erasure. The ZNet stack reserves a small portion of this space for its own use, but the rest is available to the application.
6.6.4
RAM
The SN250 integrates 5KB of SRAM. Like the Flash memory, this RAM is also mapped to both the program and data-side address spaces. On the program side, the RAM is mapped to the top 2.5k words of the program address space. The program-side mapping of the RAM is used for code when writing to or erasing the Flash memory. On the data side, the RAM is also mapped to the top of the address space, occupying the last 5KB, as shown in Figure 3 and Figure 4. Additionally, the SN250 supports a protection mechanism to prevent application code from overwriting system data stored in the RAM. To enable this, the RAM is segmented into 32byte sections, each with a configurable bit that allows or denies write access when the SN250 is running in Application Mode. Read access is always allowed to the entire RAM, and full access is always allowed when the SN250 is running in System Mode. The ZNet stack intelligently manages this protection mechanism to assist in tracking down many common application errors.
6.6.5
Registers
Table 40 provides a short description of all application-accessible registers within the SN250. Complete descriptions are provided at the end of each applicable Functional Description section. The registers are mapped to the data-side address space starting at address 0x4000. These registers allow for the control and configuration of the various peripherals and modules. The registers may only be accessed as whole word quantities; attempts to access them as bytes may result in undefined behavior. There are additional registers used by the ZNet stack when the SN250 is running in System Mode, allowing for control of the MAC, baseband, and other internal modules. These system registers are protected from being modified when the SN250 is running in Application Mode.
6.7
Encryption accelerator
The SN250 contains a hardware AES encryption engine that is attached to the CPU using a memory-mapped interface. NIST-based CCM, CCM*, CBC-MAC, and CTR modes are implemented in hardware. These modes are described in the IEEE 802.15.4-2003 specification, with the exception of CCM*, which is described in the ZigBee Security Services Specification 1.0. The ZNet stack implements a security API for applications that require security at the application level.
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Functional description--system modules
SN250
6.8
Reset detection
The SN250 contains multiple reset sources. The reset event is logged into the reset source register, which lets the CPU determine the cause of the last reset. The following reset causes are detected:
Power-on-Reset Watchdog PC rollover Software reset Core Power Dip
6.9
Power-on-Reset (POR)
Each voltage domain (1.8V Digital Core Supply VDD_CORE and Pads Supply VDD_PADS) has a power-on-reset (POR) cell. The VDD_PADS POR cell holds the always-powered high-voltage domain in reset until the following conditions have been met:
The high-voltage Pads Supply VDD_PADS voltage rises above a threshold. The internal RC clock starts and generates three clock pulses. The 1.8V POR cell holds the main digital core in reset until the regulator output voltage rises above a threshold.
Additionally, the digital domain counts 1,024 clock edges on the 24MHz crystal before releasing the reset to the main digital core. Table 11 lists the features of the SN250 POR circuitry. Table 11.
Parameter VDD_PADS POR release VDD_PADS POR assert 1.8V POR release 1.8V POR hysteresis
POR specifications
Min. 1.0 0.5 1.35 0.08 Typ. 1.2 0.6 1.5 0.1 Max. 1.4 0.7 1.65 0.12 Unit V V V V
6.10
Clock sources
The SN250 integrates three oscillators: a high-frequency 24MHz crystal oscillator, an optional low-frequency 32.768kHz crystal oscillator, and a low-frequency internal 10kHz RC oscillator.
6.10.1
High-frequency crystal oscillator
The integrated high-frequency crystal oscillator requires an external 24MHz crystal with an accuracy of 40ppm. Based upon the application Bill of Materials and current consumption requirements, the external crystal can cover a range of ESR requirements. For a lower ESR, the cost of the crystal increases but the overall current consumption decreases. Likewise, for
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SN250
Functional description--system modules higher ESR, the cost decreases but the current consumption increases. Therefore, the designer can choose a crystal to fit the needs of the application. Table 12 lists the specifications for the high-frequency crystal. Table 12.
Parameter Frequency Duty cycle Phase noise from 1kHz to 100kHz Accuracy Crystal ESR Crystal ESR Star t-up time to stable clock (max. bias) Star t-up time to stable clock (optimum bias) Current consumption Current consumption Current consumption Good crystal: 20 ESR, 10pF load Worst-case crystals (60, 18pF or 100, 10pF) At maximum bias 0.2 Initial, temperature, and aging Load capacitance of 10pF Load capacitance of 18pF - 40 40
High-frequency crystal specifications
Test Conditions Min. Typ. 24 60 - 120 + 40 100 60 1 2 0.3 0.5 1 Max. Unit MHz % dBc/Hz ppm ms ms mA mA mA
6.10.2
Low-frequency oscillator
The optional low-frequency crystal source for the SN250 is a 32.768kHz crystal. Table 13 lists the requirements for the low-frequency crystal. The low-frequency crystal may be used for applications that require greater accuracy than can be provided by the internal RC oscillator. The crystal oscillator has been designed to accept any standard watch crystal with an ESR of 100 k. Table 13.
Parameter Frequency Accuracy Load capacitance (double this each side to ground) Crystal ESR Star t-up time Current consumption Initial, temperature, and aging - 100 12.5 100 1 0.5
Low-Frequency Crystal Specifications
Test Conditions Min. Typ. 32.768 + 100 Max. Unit kHz ppm pF k S A
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Functional description--system modules
SN250
6.10.3
Internal RC oscillator
The SN250 has a low-power, low-frequency RC oscillator that runs all the time. Its nominal frequency is 10kHz. The RC oscillator has a coarse analog trim control, which is first adjusted to get the frequency as close to 10kHz as possible. This raw clock is used by the chip management block. It is also divided down to 1kHz using a variable divider to allow software to accurately calibrate it. This calibrated clock is available to the sleep timer. Timekeeping accuracy depends on temperature fluctuations the chip is exposed to, power supply impedance, and the calibration interval, but in general it will be better than 150ppm (including crystal error of 40ppm). Table 14 lists the specifications of the RC oscillator. Table 14.
Parameter Frequency Analog trim steps Frequency variation with supply For a voltage drop from 3.6V to 3.1V or 2.6V to 2.1V
RC Oscillator Specifications
Test Conditions Min. Typ. 10 1 0.5 Max. Unit kHz kHz %
6.11
Random number generator
The SN250 allows for the generation of random numbers by exposing a randomly generated bit from the RX ADC. Analog noise current is passed through the RX path, sampled by the receive ADC, and stored in a register. The value contained in this register could be used to seed a software-generated random number. The ZNet stack utilizes these random numbers to seed the Random MAC Backoff and Encryption Key Generators.
6.12
Watchdog timer
The SN250 contains a watchdog timer clocked from the internal oscillator. The watchdog is disabled by default, but can be enabled or disabled by software. If the timer reaches its time-out value of approximately 2 seconds, it will generate a reset signal to the chip. When software is running properly, the application can periodically restart this timer to prevent the reset signal from being generated. The watchdog will generate a low watermark interrupt in advance of actually resetting the chip. This low watermark interrupt occurs approximately 1.75 seconds after the timer has been restarted. This interrupt can be used to assist during application debug.
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SN250
Functional description--system modules
6.13
Sleep timer
The 16-bit sleep timer is contained in the always-powered digital block. It has the following features:
Two output compare registers, with interrupts Only Compare A Interrupt generates Wake signal Fur ther clock divider of 2N, for N = 0 to 10
The clock source for the sleep timer can be either the 32.768 kHz clock or the calibrated 1kHz clock (see Table 15). After choosing the clock source, the frequency is slowed down with a 2N prescaler to generate the final timer clock (see Table 16). Legal values for N are 0 to 10. The slowest rate the sleep timer counter wraps is 216 210 / 1kHz 67109 sec. about 1118.48 min. 18.6 hrs. Table 15.
CLK_SEL 0 1
Sleep timer clock source selection
Clock Source Calibrated 1kHz clock 32.768kHz clock
Table 16.
Sleep timer clock source prescaling
Clock Source Prescale Factor 2N 210
CLK_DIV[3:0] N = 0..10 N = 11..15
The ZNet software allows the application to define the clock source and prescaler value. Therefore, a programmable sleep/wake duty cycle can be configured according to the application requirements.
6.14
Power management
The SN250 supports three different power modes: processor ACTIVE, processor IDLE, and DEEP SLEEP. The IDLE power mode stops code execution of the XAP2b until any interrupt occurs or an external SIF wakeup command is seen. All peripherals of the SN250 including the radio continue to operate normally. The DEEP SLEEP power mode powers off most of the SN250 but leaves the critical chip functions, such as the GPIO pads and RAM powered by the High Voltage Supply (VDD_PADS). The SN250 can be woken by configuring the sleep timer to generate an interrupt after a period of time, using an external interrupt, or with the SIF interface. Activity on a serial interface may also be configured to wake the SN250, though actual reception of data is not re-enabled until the SN250 has finished waking up. Depending on the speed of the serial data, it is possible to finish waking up in the middle of a byte. Care must be taken to reset the serial interface between bytes and discard any garbage data before the rest. Another condition for wakeup is general activity on GPIO pins. The GPIO activity monitoring is described in Section 7.1. When in DEEP SLEEP, the internal regulator is disabled and VREG_OUT is turned off. All GPIO output signals are maintained in a frozen state. Additionally, the state of all registers in
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Functional description--system modules
SN250
the powered-down low-voltage domain of the SN250 is lost. Register settings for application peripherals should be preserved by the application as desired. The operation of DEEP SLEEP is controlled by ZNet APIs which automatically preserve the state of necessary system peripherals. The internal XAP2b CPU registers are automatically saved and restored to RAM by hardware when entering and leaving the DEEP SLEEP mode, allowing code execution to continue from where it left off. The event that caused the wakeup and any additional events that occurred while waking up are reported to the application via the ZNet APIs. Upon waking from DEEP SLEEP, the internal regulator is re-enabled.
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SN250
Functional description--application modules
7
Functional description--application modules
In Application Mode, access to privileged areas are blocked while access to applicationspecific modules such as GPIO, Serial Controllers (SC1 and SC2), General Purpose Timers, ADC, and Event Manager are enabled.
7.1
GPIO
The SN250 has 17 multi-purpose GPIO pins that can be configured in a variety of ways. All pins have the following programmable features:
Selectable as input, output, or bi-directional. Output can be totem pole, used as open drain or open source output for wired-OR applications. Can have internal pull-up or pull-down.
The information flow between the GPIO pin and its source are controlled by separate GPIO Data registers. The GPIO_INH and GPIO_INL registers report the input level of the GPIO pins. The GPIO_DIRH and GPIO_DIRL registers enable the output signals for the GPIO Pins. The GPIO_PUH and GPIO_PUL registers enable pull-up resistors while GPIO_PDH and GPIO_PDL registers enable pull-down resistors on the GPIO Pins. The GPIO_OUTH and GPIO_OUTL control the output level. Instead of changing the entire contents to the OUT/DIR registers with one write access, a limited change can be applied. Writing to the GPIO_SETH/L or GPIO_DIRSETH/L register changes individual register bits from 0 to 1, while data bits that are already 1 are maintained. Writing to the GPIO_CLRH/L or GPIO_DIRCLRH/L register changes individual register bits from 1 to 0, while data bits that are already 0 are maintained. Note that the value read from GPIO_OUTH/L, GPIO_SETH/L, and GPIO_CLRH/L registers may not reflect the current pin state. To observe the pin state, the GPIO_INH/L registers should be read. All registers controlling the GPIO pin definitions are unaffected by power cycling the main core voltage (VDD_CORE).
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Functional description--application modules Figure 5. GPIO control logic
VDD_PADS GPIO_PUH/L Alternate GPIO functions Note (1)
SN250
GPIO_DIRSETH/L GPIO_DIRH/L GPIO_DIRCLRH/L GPIO_SETH/L GPIO_OUTH/L GPIO_CLRH/L
Note (2) GPIO[16:0]
GPIO_CFG GPIO_PDH/L
GPIO_INH/L Note (1) : Pull-up resistor is always disabled for Alternate GPIO functions ADC 0, ADC1, ADC2, ADC3, VREF_OUT, PTI_EN and PTI_DATA. Note (2) : Pull-down resistor is always disabled for Alternate GPIO functions VREF_OUT, PTI_EN and PTI_DATA.
The GPIO_DBG register must always remain set to zero. The GPIO_CFG register controls the GPIO signal routing for alternate GPIO functions as listed in Table 17. Refer to Table 1 for individual pin alternate functions. Table 18 defines the alternate functions routed to the GPIO. To allow more flexibility, the timer signals can come from alternative sources (e.g., TIM1IA.1, TIM1IA.2, TIM1IA.3), depending on what serial controller functions are used. The Always Connected input functions labelled IRQA, IRQB, IRQC and IRQD refer to the external interrupts. GPIO8, GPIO14, GPIO15, and GPIO16 are the only pins designed to operate as external interrupts (IRQs). These pins offer individual filtering options, triggering options, and interrupt configurations. The minimum width needed to latch an unfiltered external interrupt in both level and edge triggered mode is 80ns. With the filter engaged via the GPIO_INTFIlT bit, the minimum width needed in 450ns. Other alternate functions such as timer input captures are capable of generating an interrupt based on external signals, but these other alternate functions do not contain the flexibility offered on the four external interrupts (IRQs). When the core is powered down, peripherals stop driving correct output signals. To maintain correct output signals, the system software will ensure that the GPIO output signals are frozen before going into deep sleep. Monitoring circuitry is in place to detect when the logic state of GPIO input pins change. The lower 16 GPIO pins that should be monitored can be chosen by software with the GPIO_WAKEL register. The resulting event can be used for waking up from deep sleep as described in Section 6.14.
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SN250 Table 17. GPIO pin configurations
Mode
Functional description--application modules
GPIO_CFG[15:0]
0010 0000 0000 0000 DEFAULT ---1 ---- ---- ---- Enable PTI_EN + PTI_DATA ---0 ---1 ---- ---- Enable analog input ADC0 ---0 ---0 ---- ------0 --1- ---- ---- Enable analog input ADC1 ---0 --0- ---- ------- -1-- ---- ---- Enable analog input ADC2 ---- -0-- ---- -----1- ---- ---- ---- Enable REG_EN --0- 1--- ---- ---- Enable analog input ADC3 --0- 0--- ---- ----1-- ---- ---- ---- Enable VREF_OUT -0-- ---- ---- ------- ---- 0000 ---- Enable ---- ---- 0001 ---- Enable SC1-2 + SC2-2 Enable GPIO8 Enable GPIO7 Enable GPIO6 Enable GPIO5 EnableGPIO4
+ CAP2-0 + CAP1-0 mode+ GPIO[12,11,10,9,3,2,1,0] + CAP2-0 + CAP1-0 mode+GPIO[12,11, 3, 0]
---- ---- 0010 ---- Enable SC1-4A + SC2-4S + CAP2-2 + CAP1-2h mode ---- ---- 0011 ---- Enable SC1-3M + SC2-3M + CAP2-2 + CAP1-2 ---- ---- 0100 ---- Enable ---- ---- 0101 ---- Enable SC1-2 SC2-2 + CAP2-0 + CAP1-0 mode+GPIO[12, 3 ] 0] ] 3 ]
mode+GPIO[12,11,10,9,3,
+ SC2-4S + CAP2-0 + CAP1-2h mode+GPIO[12,11 mode+GPIO[ mode+GPIO[12
---- ---- 0110 ---- Enable SC1-4A + SC2-3M + CAP2-2 + CAP1-2 ---- ---- 0111 ---- Enable SC1-3M ---- ---- 1000 ---- Enable ---- ---- 1001 ---- Enable SC1-2 ---- ---- 1010 ---- Enable SC1-4A ---- ---- 1011 ---- Enable SC1-3M + SC2-2 ---- ---- 1100 ---- Enable ---- ---- 1101 ---- Enable SC1-2 ---- ---- 1110 ---- Enable SC1-4A + SC2-2 + CAP2-1 + CAP1-0
3,2,1,0] ] 3 ]
SC2-4S + CAP2-0 + CAP1-1h mode+GPIO[12,11,10,9 + SC2-3M + CAP2-0 + CAP1-2 + CAP2-1 + CAP1-0 + CAP2-2 + CAP1-0 mode+GPIO[12,11, mode+GPIO[ mode+GPIO[12
3,2,1,0] 3, 0] ]
SC2-3M + CAP2-0 + CAP1-1 + CAP2-0 + CAP1-0 + CAP2-2 + CAP1-0
mode+GPIO[12,11,10,9,3 mode+GPIO[12,11, mode+GPIO[
3,2,1,0] 3, 0] ]
---- ---- 1111 ---- Enable SC1-3M + SC2-4S + CAP2-2 + CAP1-2h mode+GPIO[12 ---- ---- ---- ---1 Enable TMR2OA ---- ---- ---- ---0 ---- ---- ---- --1- Enable TMR2OB ---- ---- ---- --0---- ---- ---- -1-- Enable TMR1OA ---- ---- ---- -0----- ---- ---- 1--- Enable TMR1OB ---- ---- ---- 0--EnableGPIO16 Enable GPIO15 Enable GPIO14 Enable GPIO13
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Functional description--application modules Table 18. GPIO pin functions
Analog Function
SN250
Always GPIO Connected Pin Input Functions 0 1 2 3 4 5 6 7 8 9 10 11 12 13 IO IO IO IO IO IO IO IO IO / IRQA IO IO IO IO IO
Timer Functions
Serial Digital Functions
Output Current Drive Standard Standard Standard Standard
TMR1IA.1 (when CAP1-0 mode) TMR2IA.2 (when CAP2-1 mode) TMR2IB.2 (when CAP2-1 mode) TMR1IB.1 (when CAP1-0 mode)
MOSI MISO / SDA MSCLK / SCL nSSEL (input) PTI_EN PTI_DATA ADC0 input ADC1 input ADC2 input REG_EN (open collector enable for external regulator) ADC3 input VREF_OUT
Standard Standard Standard Standard Standard Standard Standard Standard Standard High
TMR2CLK, TMR1ENMSK
TMR1CLK, TMR2ENMSK TMR1IA.2 TXD / MO / MSDA (when CAP1-1 or CAP1-1h mode) TMR1IB.2 (when CAP1-1 mode) RXD / MI / MSCL TMR2IA.1 (when CAP2-0 mode) nCTS / MCLK TMR2IB.1 (when CAP2-0 mode) nRTS TMR2OA TMR1IA.3 (when CAP1-2h or CAP1-2 mode) TMR2OB TMR1IB.3 (when CAP1-2 mode) TMR1OA TMR2IA.3 (when CAP2-2 mode) TMR1OB TMR2IB.3 (when CAP2-2 mode)
14 15 16
IO / IRQB IO / IRQC IO / IRQD
High High High
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SN250
Functional description--application modules
7.1.1
Registers
GPIO_CFG [0x4712]
15 0-R 0 14 0-RW 13 1-RW 12 0-RW 11 0-RW GPIO_CFG GPIO_CFG 0-RW 7 GPIO_CFG 0-RW 6 [14:0] 0-RW 5 0-RW 4 0-RW 3 0-RW 2 0-RW 1 0-RW 0 10 0-RW 9 0-RW 8 0-RW
GPIO configuration modes. Refer to Table 1 and Table 17 for the mode settings.
GPIO_INH [0x4700]
15 0-R 0 0 0-R 7 GPIO_INH 14 0-R 0 0 0-R 6 [0] 13 0-R 0 0 0-R 5 12 0-R 0 0 0-R 4 11 0-R 0 0 0-R 3 10 0-R 0 0 0-R 2 9 0-R 0 0 0-R 1 8 0-R 0 GPIO_INH 0-R 0
Read the input level of GPIO[16] pin.
GPIO_INL [0x4702]
15 0-R 14 0-R 13 0-R 12 0-R GPIO_INL GPIO_INL 0-R 7 GPIO_INL 0-R 6 [15:0] 0-R 5 0-R 4 0-R 3 0-R 2 0-R 1 0-R 0 11 0-R 10 0-R 9 0-R 8 0-R
Read the input level of GPIO[15:0] pins.
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Functional description--application modules
SN250
GPIO_OUTH [0x4704]
15 0-R 0 0 0-R 7 GPIO_OUTH 14 0-R 0 0 0-R 6 [0] 13 0-R 0 0 0-R 5 12 0-R 0 0 0-R 4 11 0-R 0 0 0-R 3 10 0-R 0 0 0-R 2 9 0-R 0 0 0-R 1 8 0-R 0 GPIO_OUTH 0-RW 0
Write the output level of GPIO[16] pin. The value read may not match the actual value on the pin.
GPIO_OUTL [0x4706]
15 0-RW 14 0-RW 13 0-RW 12 0-RW 11 0-RW 10 0-RW 9 0-RW 8 0-RW
GPIO_OUTL GPIO_OUTL 0-RW 7 GPIO_OUTL 0-RW 6 [15:0] 0-RW 5 0-RW 4 0-RW 3 0-RW 2 0-RW 1 0-RW 0
Write the output level of GPIO[15:0] pins. The value read may not match the actual value on the pin.
GPIO_SETH [0x4708]
15 0-R 0 0 0-R 7 GPIO_SETH 14 0-R 0 0 0-R 6 [0] 13 0-R 0 0 0-R 5 12 0-R 0 0 0-R 4 11 0-R 0 0 0-R 3 10 0-R 0 0 0-R 2 9 0-R 0 0 0-R 1 8 0-R 0 GPIO_SETH 0-W 0
Set the output level of GPIO[16] pin. Only writing ones into this register will have an effect. Any bit that has one written to it will cause the corresponding bit in GPIO_OUTH to become 1.
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SN250
Functional description--application modules
GPIO_SETL [0x470A]
15 0-W 14 0-W 13 0-W 12 0-W 11 0-W 10 0-W 9 0-W 8 0-W
GPIO_SETL GPIO_SETL 0-W 7 GPIO_SETL 0-W 6 [15:0] 0-W 5 0-W 4 0-W 3 0-W 2 0-W 1 0-W 0
Set the output level of GPIO[15:0] pins. Only writing ones into this register will have an effect. Any bit that has one written to it will cause the corresponding bit in GPIO_OUTL to become 1.
GPIO_CLRH [0x470C]
15 0-R 0 0 0-R 7 GPIO_CLRH 14 0-R 0 0 0-R 6 [0] 13 0-R 0 0 0-R 5 12 0-R 0 0 0-R 4 11 0-R 0 0 0-R 3 10 0-R 0 0 0-R 2 9 0-R 0 0 0-R 1 8 0-R 0 GPIO_CLRH 0-W 0
Clear the output level of GPIO[16] pin. Only writing ones into this register will have an effect. Any bit that has one written to it will cause the corresponding bit in GPIO_OUTH to become 0.
GPIO_CLRL [0x470E]
15 0-W 14 0-W 13 0-W 12 0-W 11 0-W 10 0-W 9 0-W 8 0-W
GPIO_CLRL GPIO_CLRL 0-W 7 GPIO_CLRL 0-W 6 [15:0] 0-W 5 0-W 4 0-W 3 0-W 2 0-W 1 0-W 0
Clear the output level of GPIO[15:0] pins. Only writing ones into this register will have an effect. Any bit that has one written to it will cause the corresponding bit in GPIO_OUTL to become 0.
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Functional description--application modules
SN250
GPIO_DIRH [0x4714]
15 0-R 0 0 0-R 7 GPIO_DIRH 14 0-R 0 0 0-R 6 [0] 13 0-R 0 0 0-R 5 12 0-R 0 0 0-R 4 11 0-R 0 0 0-R 3 10 0-R 0 0 0-R 2 9 0-R 0 0 0-R 1 8 0-R 0 GPIO_DIRH 0-RW 0
Enable the output of GPIO[16] pin.
GPIO_DIRL [0x4716]
15 0-RW 14 0-RW 13 0-RW 12 0-RW 11 0-RW 10 0-RW 9 0-RW 8 0-RW
GPIO_DIRL GPIO_DIRL 0-RW 7 GPIO_DIRL 0-RW 6 [15:0] 0-RW 5 0-RW 4 0-RW 3 0-RW 2 0-RW 1 0-RW 0
Enable the output of GPIO[15:0] pins.
GPIO_DIRSETH [0x4718]
15 0-R 0 0 0-R 7 GPIO_DIRSETH 14 0-R 0 0 0-R 6 [0] 13 0-R 0 0 0-R 5 12 0-R 0 0 0-R 4 11 0-R 0 0 0-R 3 10 0-R 0 0 0-R 2 9 0-R 0 0 0-R 1 8 0-R 0 GPIO_ DIRSETH 0-W 0
Set the output enable of GPIO[16] pin. Only writing ones into this register will have an effect. Any bit that has one written to it will cause the corresponding bit in GPIO_DIRH to become 1.
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SN250
Functional description--application modules
GPIO_DIRSETL [0x471A]
15 0-W 14 0-W 13 0-W 12 0-W 11 0-W 10 0-W 9 0-W 8 0-W
GPIO_DIRSETL GPIO_DIRSETL 0-W 7 GPIO_DIRSETL 0-W 6 [15:0] 0-W 5 0-W 4 0-W 3 0-W 2 0-W 1 0-W 0
Set the output enable of GPIO[15:0] pins. Only writing ones into this register will have an effect. Any bit that has one written to it will cause the corresponding bit in GPIO_DIRL to become 1.
GPIO_DIRCLRH [0x471C]
15 0-R 0 0 0-R 7 14 0-R 0 0 0-R 6 13 0-R 0 0 0-R 5 12 0-R 0 0 0-R 4 11 0-R 0 0 0-R 3 10 0-R 0 0 0-R 2 9 0-R 0 0 0-R 1 8 0-R 0 GPIO_ DIRCLRH 0-W 0
GPIO_DIRCLRH [0]
Clear the output enable of GPIO[16] pin. Only writing ones into this register will have an effect. Any bit that has one written to it will cause the corresponding bit in GPIO_DIRH to become 0.
GPIO_DIRCLRL [0x471E]
15 0-W 14 0-W 13 0-W 12 0-W 11 0-W 10 0-W 9 0-W 8 0-W
GPIO_DIRCLRL GPIO_DIRCLRL 0-W 7 GPIO_DIRCLRL 0-W 6 [15:0] 0-W 5 0-W 4 0-W 3 0-W 2 0-W 1 0-W 0
Clear the output enable of GPIO[15:0] pins. Only writing ones into this register will have an effect. Any bit that has one written to it will cause the corresponding bit in GPIO_DIRL to become 0.
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Functional description--application modules
SN250
GPIO_PDH [0x4720]
15 0-R 0 0 0-R 7 GPIO_PDH 14 0-R 0 0 0-R 6 [0] 13 0-R 0 0 0-R 5 12 0-R 0 0 0-R 4 11 0-R 0 0 0-R 3 10 0-R 0 0 0-R 2 9 0-R 0 0 0-R 1 8 0-R 0 GPIO_PDH 0-RW 0
Set this bit to enable pull-down resistors on GPIO[16] pin.
GPIO_PDL [0x4722]
15 0-RW 14 0-RW 13 0-RW 12 0-RW 11 0-RW 10 0-RW 9 0-RW 8 0-RW
GPIO_PDL GPIO_PDL 0-RW 7 GPIO_PDL 0-RW 6 [15:0] 0-RW 5 0-RW 4 0-RW 3 0-RW 2 0-RW 1 0-RW 0
Set this bit to enable pull-down resistors on GPIO[15:0] pins.
GPIO_PUH [0x4724]
15 0-R 0 0 0-R 7 GPIO_PUH 14 0-R 0 0 0-R 6 [0] 13 0-R 0 0 0-R 5 12 0-R 0 0 0-R 4 11 0-R 0 0 0-R 3 10 0-R 0 0 0-R 2 9 0-R 0 0 0-R 1 8 0-R 0 GPIO_PUH 0-RW 0
Set this bit to enable pull-up resistors on GPIO[16] pin.
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SN250
Functional description--application modules
GPIO_PUL [0x4726]
15 0-RW 14 0-RW 13 0-RW 12 0-RW 11 0-RW 10 0-RW 9 0-RW 8 0-RW
GPIO_PUL GPIO_PUL 0-RW 7 GPIO_PUL 0-RW 6 [15:0] 0-RW 5 0-RW 4 0-RW 3 0-RW 2 0-RW 1 0-RW 0
Set this bit to enable pull-up resistors on GPIO[15:0] pins.
GPIO_WAKEL [0x4728]
15 0-RW 14 0-RW 13 0-RW 12 0-RW 11 0-RW 10 0-RW 9 0-RW 8 0-RW
GPIO_WAKEL GPIO_WAKEL 0-RW 7 GPIO_WAKEL 0-RW 6 [15:0] 0-RW 5 0-RW 4 0-RW 3 0-RW 2 0-RW 1 0-RW 0
Setting bits will enable GPIO wakeup monitoring for changing states on GPIO[15:0] pins.
GPIO_INTCFGA [0x4630]
15 0-R 0 14 0-R 0 GPIO_INTMOD 0-RW 7 GPIO_INTFILT GPIO_INTMOD 0-RW 6 [8] [7:5] 0-RW 5 13 0-R 0 12 0-R 0 0 0-R 4 11 0-R 0 0 0-R 3 10 0-R 0 0 0-R 2 9 0-R 0 0 0-R 1 8 0-RW GPIO_ INTFILT 0 0-R 0
Set this bit to enable GPIO IRQA filter. GPIO IRQA input edge triggering selection: 0 = disabled; 1 = rising; 2 = falling; 3 = both edges; 4 = active high triggered; 5 = active low trigger; 6,7 = reserved.
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Functional description--application modules
SN250
GPIO_INTCFGB [0x4632]
15 0-R 0 14 0-R 0 GPIO_INTMOD 0-RW 7 GPIO_INTFILT GPIO_INTMOD 0-RW 6 [8] [7:5] 0-RW 5 13 0-R 0 12 0-R 0 0 0-R 4 11 0-R 0 0 0-R 3 10 0-R 0 0 0-R 2 9 0-R 0 0 0-R 1 8 0-RW GPIO_INTFILT 0 0-R 0
Set this bit to enable GPIO IRQB filter GPIO IRQB input edge triggering selection: 0 = disabled; 1 = rising; 2 = falling; 3 = both edges; 4 = active high triggered; 5 = active low trigger; 6,7 = reserved.
GPIO_INTCFGC [0x4634]
15 0-R 0 14 0-R 0 GPIO_INTMOD 0-RW 7 GPIO_INTFILT GPIO_INTMOD 0-RW 6 [8] [7:5] 0-RW 5 13 0-R 0 12 0-R 0 0 0-R 4 11 0-R 0 0 0-R 3 10 0-R 0 0 0-R 2 9 0-R 0 0 0-R 1 8 0-RW GPIO_INTFILT 0 0-R 0
Set this bit to enable GPIO IRQC filter. GPIO IRQC input edge triggering selection: 0 = disabled; 1 = rising; 2 = falling; 3 = both edges; 4 = active high triggered; 5 = active low trigger; 6,7 = reserved.
GPIO_INTCFGD [0x4636]
15 0-R 0 14 0-R 0 GPIO_INTMOD 0-RW 7 GPIO_INTFILT GPIO_INTMOD 0-RW 6 [8] [7:5] 0-RW 5 13 0-R 0 12 0-R 0 0 0-R 4 11 0-R 0 0 0-R 3 10 0-R 0 0 0-R 2 9 0-R 0 0 0-R 1 8 0-RW GPIO_INTFILT 0 0-R 0
Set this bit to enable GPIO IRQD filter. GPIO IRQD input edge triggering selection: 0 = disabled; 1 = rising; 2 = falling; 3 = both edges; 4 = active high triggered; 5 = active low trigger; 6,7 = reserved.
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SN250
Functional description--application modules
INT_GPIOCFG [0x4628]
15 0-R 0 0 0-R 7 INT_GPIOD INT_GPIOC INT_GPIOB INT_GPIOA 14 0-R 0 0 0-R 6 [3] [2] [1] [0] 13 0-R 0 0 0-R 5 12 0-R 0 0 0-R 4 11 0-R 0 INT_GPIOD 0-RW 3 10 0-R 0 INT_GPIOC 0-RW 2 9 0-R 0 INT_GPIOB 0-RW 1 8 0-R 0 INT_GPIOA 0-RW 0
GPIO IRQD interrupt enable. GPIO IRQC interrupt enable. GPIO IRQB interrupt enable. GPIO IRQA interrupt enable.
INT_GPIOFLAG [0x4610]
15 0-R 0 0 0-R 7 INT_GPIOD INT_GPIOC INT_GPIOB INT_GPIOA 14 0-R 0 0 0-R 6 [3] [2] [1] [0] 13 0-R 0 0 0-R 5 12 0-R 0 0 0-R 4 11 0-R 0 INT_GPIOD 0-RW 3 10 0-R 0 INT_GPIOC 0-RW 2 9 0-R 0 INT_GPIOB 0-RW 1 8 0-R 0 INT_GPIOA 0-RW 0
GPIO IRQD interrupt pending. GPIO IRQC interrupt pending. GPIO IRQB interrupt pending. GPIO IRQA interrupt pending.
GPIO_DBG [0x4710]
15 0-R 0 0 0-R 7 GPIO_DBG 14 0-R 0 0 0-R 6 [1:0] 13 0-R 0 0 0-R 5 12 0-R 0 0 0-R 4 11 0-R 0 0 0-R 3 10 0-R 0 0 0-R 2 9 0-R 0 GPIO_DBG 0-RW 1 0-RW 0 8 0-R 0
This register must remain zero.
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Functional description--application modules
SN250
7.2
Serial controller SC1
The SN250 SC1 module provides asynchronous (UART) or synchronous (SPI or I2C) serial communications. Figure 6 is a block diagram of the SC1 module. Figure 6. SC1 block diagram
The full-duplex interface of the SC1 module can be configured into one of these three communication modes, but it cannot run them simultaneously. To reduce the interrupt service requirements of the CPU, the SC1 module contains buffered data management schemes for the three modes. A dedicated, buffered DMA controller is available to the SPI and UART controllers while a FIFO is available to all three modes. In addition, a SC1 data register allows the software application direct access to the SC1 data within all three modes. Finally, the SC1 routes the interface signals to GPIO pins. These are shared with other functions and are controlled by the GPIO_CFG register. For selecting alternate pin functions, please refer to Table 17 and Table 18.
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SN250
Functional description--application modules
7.2.1
UART mode
The SC1 UART controller is enabled with SC1_MODE set to 1. The UART mode contains the following features:
Baud rate (300 bps up to 921 Kbps) Data bits (7 or 8) Parity bits (none, odd, or even) Stop bits (1 or 2) TXD RXD nRTS (optional) nCTS (optional)
The following signals can be made available on GPIO pins:
The SC1 UART module obtains its reference baud-rate clock from a programmable baud generator. Baud rates are set by a clock division ratio from the 24MHz clock: rate = 24MHz / ( 2 ( N + (0.5 F) ) ) The integer portion, N, is written to the SC1_UARTPER register and the fractional remainder, F, to the SC1_UARTFRAC register. Table 19 lists the supported baud rates with associated baud rate error. The minimum allowable setting for SC1_UARTPER is 8. Table 19. UART baud rates
SC1_UARTPER 40000 2500 1250 625 312 208 104 26 13 SC1_UARTFRAC 0 0 0 0 1 1 0 0 0 Baud Rate Error (%) 0 0 0 0 0 - 0.08 0.16 0.16 0.16
Baud Rate (bps) 300 4800 9600 19200 38400 57600 115200 460800 921600
The UART module supports various frame formats depending upon the number of data bits (SC1_UART8BIT), the number of stop bits (SC1_UART2STP), and the parity (SC1_UARTPAR plus SC1_UARTODD). The register bits SC1_UART8BIT, SC1_UART2STP, SC1_UARTPAR, and SC1_UARTODD are defined within the SC1_UARTCFG register. In addition, the UART module supports flow control by setting SC1_UARTFLOW, SC1_UARTAUTO, and SC1_UARTRTS in the SC1_UARTCFG register (see Table 20).
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Functional description--application modules Table 20. Configuration table for the UART module
SC1_UARTCFG SC1_MODE 1 1 SC1_UARTFLOW SC1_UARTAUTO 0 1 SC1_UARTRTS -
SN250
GPIO_CFG[7:4] GPIO-Pin Function SC1-2 mode SC1-2 mode TXD/RXD output/input Illegal TXD/RXD/CTS output/input/input RTS output = ON/OFF TXD/RXD/CTS output/input/input RTS output = ON if 2 or more bytes will fit in receive buffer Reser ved Illegal Illegal
1
1
0
0/1
SC1-4A mode
1
1
1
-
SC1-4A mode
1 1 1
0 0 -
1 0 -
-
SC1-4A mode SC1-4A mode SC1-3M mode
Characters transmitted and received are passed through transmit and receive FIFOs. The transmit and receive FIFOs are 4 bytes deep. The FIFOs are accessed under software control by accessing the SC1_DATA data register or under hardware control by the SC1 DMA. When a transmit character is written to the (empty) transmit FIFO, the register bit SC1_UARTTXIDLE in the SC1_UARTSTAT register clears to indicate that not all characters are transmitted yet. Further transmit characters can be written to the transmit FIFO until it is full, which causes the register bit SC1_UARTTXFREE in the SC1_UARTSTAT register to clear. After shifting one transmit character to the TXD pin, space for one transmit character becomes available in the transmit FIFO. This causes the register bit SC1_UARTTXFREE in the SC1_UARTSTAT register to get set. After all characters are shifted out, the transmit FIFO empties, which causes the register bit SC1_UARTTXIDLE in the SC1_UARTSTAT register to get set. A received character is stored with its parity and frame error status in the receive FIFO. The register bit SC1_UARTRXVAL in the SC1_UARTSTAT register is set to indicate that not all received characters are read out from the receive FIFO. The error status of a received byte is available with the register bits SC1_UARTPARERR and SC1_UARTFRMERR in the SC1_UARTSTAT register. When the DMA controller is transferring the data from the receive FIFO to a memory buffer, it checks the stored parity and frame error status flags. When an error is flagged, the SC1_RXERRA/B register is updated, marking the offset to the first received character with parity or frame error. When the 4-character receive FIFO contains 3 characters, flow control needs to be used to avoid an overflow event. One method is to use software handshaking by transmitting reserved XON/XOFF characters which are interpreted by the transmitting terminal to pause further transmissions (to the receive FIFO). Another method is to use hardware handshaking using XOFF assertion through the RTS signal.
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SN250
Functional description--application modules There are two schemes available to assert the RTS signal. The first scheme is to initiate RTS assertion with software by setting the register bit SC1_UARTRTS in the SC1_UARTCFG register. The second scheme is to assert RTS automatically depending on the fill state of the receive FIFO. This is enabled with the register bit SC1_UARTAUTO in the SC1_UARTCFG register. The UART also contains overrun protection for both the FIFO and DMA options. If the transmitting terminal continues to transmit characters to the receive FIFO, only 4 characters are stored in the FIFO. Additional characters are dropped, and the register bit SC1_UARTRXOVF in the SC1_UARTSTAT register is set. Should this receive overrun occur during DMA operation, the SC1_RXERRA/B registers mark the error-offset. The RX FIFO hardware generates the INT_SCRXOVF interrupt, but the DMA register will not indicate the error condition until the RX FIFO is drained. Once the DMA marks a RX error, there are two conditions that will clear the error indication: setting the appropriate SC_TX/RXDMARST bit in the SC1_DMACTRL register, or loading the appropriate DMA buffer after it has unloaded. Interrupts are generated on the following events:
Transmit FIFO empty and last character shifted out (0 to 1 transition of SC1_UARTTXIDLE) Transmit FIFO changed from full to not full (0 to 1 transition of SC1_UARTTXFREE) Receive FIFO changed from empty to not empty (0 to 1 transition of SC1_UARTRXVAL) Transmit DMA buffer A/B complete (1 to 0 transition of SC_TXACTA/B) Receive DMA buffer A/B complete (1 to 0 transition of SC_RXACTA/B) Character received with Parity error Character received with Frame error Received and lost character while receive FIFO was full (Receive overrun error)
To generate interrupts to the CPU, the interrupt masks in the INT_SC1CFG and INT_CFG registers must be enabled.
7.2.2
SPI master mode
The SPI mode of the SC1 is master mode only. It has a fixed word length of 8 bits. The SC1 SPI controller is enabled with SC1_MODE set to 2 and register bit SC_SPIMST set in the SC1_SPICFG register. The SPI mode has the following features:
Full duplex operation Programmable clock frequency (12MHz max.) Programmable clock polarity and clock phase Selectable data shift direction (either LSB or MSB first) MO (master out) MI (master in) MCLK (serial clock)
The following signals can be made available on the GPIO pins:
The SC1 SPI module obtains its reference clock from a programmable clock generator. Clock rates are set by a clock division ratio from the 24MHz clock: rate = 24MHz / ( 2 (LIN + 1) 2EXP )
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Functional description--application modules
SN250
EXP is written to the SC1_RATEEXP register and LIN to the SC1_RATELIN register. Since the range for both values is 0 to 15, the fastest data rate is 12Mbps and the slowest rate is 22.9bps. The SC1 SPI master supports various frame formats depending upon the clock polarity (SC_SPIPOL), clock phase (SC_SPIPHA), and direction of data (SC_SPIORD) (see Table 21). The register bits SC_SPIPOL, SC_SPIPHA, and SC_SPIORD are defined within the SC1_SPICFG register. Note: Switching the SPI configuration from SC_SPIPOL=1 to SC_SPIPOL=0 without subsequently setting SC1_MODE=0 and reinitializing the SPI will cause an extra byte (0xFE) to be transmitted immediately before the first intended byte. SC1 SPI master frame format
GPIO_CFG[7:4] SC1-3M mode SC1-3M mode SC1-3M mode SC1-3M mode SC1-3M Same as above except LSB first instead of MSB first mode SC1-2 mode Illegal
Table 21.
SC1_SPICFG SC_SPIORD SC_SPIMST SC_SPIPHA SC_SPIPOL SC1_MODE
Frame Format
2
1
0
0
0
2
1
0
0
1
2
1
0
1
0
2
1
0
1
1
2 2 2
1 1 1
1 -
-
-
SC1-4A Illegal mode
Serialized SC1 SPI transmit data is driven to the output pin MO. SC1 SPI master data is received from the input pin MI. To generate slave select signals to SPI slave devices, other GPIO pins have to be used and their assertion must be controlled by software. Characters transmitted and received are passed through transmit and receive FIFOs. The transmit and receive FIFOs are 4 bytes deep. These FIFOs are accessed under software control by accessing the SC1_DATA data register or under hardware control using a DMA controller.
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SN250
Functional description--application modules When a transmit character is written to the (empty) transmit FIFO, the register bit SC_SPITXIDLE in the SC1_SPISTAT register clears and indicates that not all characters are transmitted yet. Further transmit characters can be written to the transmit FIFO until it is full, which causes the register bit SC_SPITXFREE in the SC1_SPISTAT register to clear. After shifting one transmit character to the MO pin, space for one transmit character becomes available in the transmit FIFO. This causes the register bit SC_SPITXFREE in the SC1_SPISTAT register to get set. After all characters are shifted out, the transmit FIFO empties, which causes the register bit SC_SPITXIDLE in the SC1_SPISTAT register to get set also. Any character received is stored in the (empty) receive FIFO. The register bit SC_SPIRXVAL in the SC1_SPISTAT register is set to indicate that not all received characters are read out from receive FIFO. If software or DMA is not reading from the receive FIFO, the receive FIFO will store up to 4 characters. Any further reception is dropped and the register bit SC_SPIRXOVF in the SC1_SPISTAT register is set. The RX FIFO hardware generates the INT_SCRXOVF interrupt, but the DMA register will not indicate the error condition until the RX FIFO is drained. Once the DMA marks a RX error, there are two conditions that will clear the error indication: setting the appropriate SC_TX/RXDMARST bit in the SC1_DMACTRL register, or loading the appropriate DMA buffer after it has unloaded. Receiving a character always requires transmitting a character. In a case when a long stream of receive characters is expected, a long sequence of (dummy) transmit characters must be generated. To avoid software or transmit DMA initiating these transfers (and consuming unnecessary bandwidth), the SPI serializer can be instructed to retransmit the last transmitted character, or to transmit a busy token (0xFF), which is determined by the register bit SC_SPIRPT in the SC1_SPICFG register. This functionality can only be enabled (or disabled) when the transmit FIFO is empty and the transmit serializer is idle, as indicated by a cleared SC_SPITXIDLE register bit in the SC1_SPISTAT register. Every time an automatic character transmission is started, a transmit underrun is detected (as there is no data in transmit FIFO), and the register bit INT_SCTXUND in the INT_SC1FLAG register is set. Note that after disabling the automatic character transmission, the reception of new characters stops and the receive FIFO holds characters just received.
Note:
The event Receive DMA complete does not automatically mean receive FIFO empty. Interrupts are generated on the following events:
Transmit FIFO empty and last character shifted out (0 to 1 transition of SC_SPITXIDLE) Transmit FIFO changed from full to not full (0 to 1 transition of SC_SPITXFREE) Receive FIFO changed from empty to not empty (0 to 1 transition of SC_SPIRXVAL) Transmit DMA buffer A/B complete (1 to 0 transition of SC_TXACTA/B) Receive DMA buffer A/B complete (1 to 0 transition of SC_RXACTA/B) Received and lost character while receive FIFO was full (Receive overrun error) Transmitted character while transmit FIFO was empty (Transmit underrun error)
To generate interrupts to the CPU, the interrupt masks in the INT_SC1CFG and INT_CFG registers must be enabled.
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Functional description--application modules
SN250
7.2.3
I2C master mode
The SC1 I2C controller is only available in master mode. The SC1 I2C controller is enabled with SC1_MODE set to 3. The I2C Master controller supports Standard (100 Kbps) and Fast (400 Kbps) I2C modes. Address arbitration is not implemented, so multiple master applications are not supported. The I2C signals are pure open-collector signals, and external pull-up resistors are required. The SC1 I2C mode has the following features:
Programmable clock frequency (400kHz max.) Suppor ts both 7-bit and 10-bit addressing MSDA (serial data) MSCL (serial clock)
The following signals can be made available on the GPIO pins:
The I2C Master controller obtains its reference clock from a programmable clock generator. Clock rates are set by a clock division ratio from the 24MHz clock:
24 MHz Nominal Rate = ------------------------------------------------EXP 2 (LIN + 1 ) 2
EXP is written to the SC1_RATEEXP register and LIN to the SC1_RATELIN register. Table 22 shows the rate settings for Standard I2C (100 Kbps) and Fast I2C (400 Kbps) operation. Table 22. I2C nominal rate programming
SC1_RATELIN 14 15 14 SC1_RATEEXP 3 1 1
Nominal Rate 100 Kbps 375 Kbps 400 Kbps
Note that at 400 Kbps, the I2C specification requires the minimum low period of SCL to be 1.3s. To be strictly I2C compliant, the rate needs to be lowered to 375 Kbps. The I2C Master controller supports generation of various frame segments controlled with the register bits SC_I2CSTART, SC_I2CSTOP, SC_I2CSEND, and SC_I2CRECV in the SC1_I2CCTRL1 registers. Table 23 summarizes these frames.
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SN250 Table 23. SC1 I2C master frame segments
GPIO_CFG[7:4]
Functional description--application modules
SC1_I2CCTRL1 SC_I2CSTART SC_I2CRECV SC_I2CSEND SC_I2CSTOP SC1_MODE
Frame Segments
3
1
0
0
0
SC1-2 mode
3
0
1
0
0
SC1-2 mode
3
0
0
1
0
SC1-2 mode
3
0
0
0
1
SC1-2 mode
3
0 1 1
0 1 1 -
0 1 1 -
0 1 1
SC1-2 mode
No pending frame segment
3
SC1-2 mode
Illegal
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Functional description--application modules Table 23. SC1 I2C master frame segments (continued)
GPIO_CFG[7:4]
SN250
SC1_I2CCTRL1 SC_I2CSTART SC_I2CSEND SC_I2CRECV SC_I2CSTOP SC1_MODE
Frame Segments
3 3
-
-
-
-
SC1-4M Illegal mode SC1-4A Illegal mode
Full I2C frames have to be constructed under software control by generating individual I2C segments. All necessary segment transitions are shown in Figure 7. ACK or NACK generation of an I2C receive frame segment is determined with the register bit SC_I2CACK in the SC1_I2CCTRL2 register. Figure 7. I2C segment transitions
Generation of a 7-bit address is accomplished with one transmit segment. The upper 7 bits of the transmitted character contain the 7-bit address. The remaining lower bit contains the command type ("read" or "write"). Generation of a 10-bit address is accomplished with two transmit segments. The upper 5 bits of the first transmit character must be set to 0x1E. The next 2 bits are for the 2 most significant bits of the 10-bit address. The remaining lower bit contains the command type
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SN250
Functional description--application modules ("read" or "write"). The second transmit segment is for the remaining 8 bits of the 10-bit address. Characters received and transmitted are passed through receive and transmit FIFOs. The SC1 I2C master transmit and receive FIFOs are 1-byte deep. These FIFOs are accessed under software control. (Re)star t and stop segments are initiated by setting the register bits SC_I2CSTART or SC_I2CSTOP in the SC1_I2CCTRL1 register followed by waiting until they have cleared. Alternatively, the register bit SC_I2CCMDFIN in the SC1_I2CSTAT can be used for waiting. To initiate a transmit segment, the data have to be written to the SC1_DATA data register, followed by setting the register bit SC_I2CSEND in the SC1_I2CCTRL1 register, and completed by waiting until it clears. Alternatively, the register bit SC_I2CTXFIN in the SC1_I2CSTAT can be used for waiting. A receive segment is initiated by setting the register bit SC_I2CRECV in the SC1_I2CCTRL1 register, waiting until it clears, and then reading from the SC1_DATA data register. Alternatively, the register bit SC_I2CRXFIN in the SC1_I2CSTAT can be used for waiting. Now the register bit SC_I2CRXNAK in the SC1_I2CSTAT register indicates if a NACK or ACK was received from an I2C slave device. Interrupts are generated on the following events:
Bus command (SC_I2CSTART/SC_I2CSTOP) completed (0 to 1 transition of SC_I2CCMDFIN) Character transmitted and slave device responded with NACK Character transmitted (0 to 1 transition of SC_I2CTXFIN) Character received (0 to 1 transition of SC_I2CRXFIN) Received and lost character while receive FIFO was full (Receive overrun error) Transmitted character while transmit FIFO was empty (Transmit underrun error)
To generate interrupts to the CPU, the interrupt masks in the INT_SC1CFG and INT_CFG registers must be enabled.
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Functional description--application modules
SN250
7.2.4
Registers
SC1_MODE [0x44AA]
15 0-R 0 0 0-R 7 SC1_MODE 14 0-R 0 0 0-R 6 [1:0] 13 0-R 0 0 0-R 5 12 0-R 0 0 0-R 4 11 0-R 0 0 0-R 3 10 0-R 0 0 0-R 2 9 0-R 0 SC1_MODE 0-RW 1 0-RW 0 8 0-R 0
SC1 Mode: 0 = disabled; 1 = UART mode; 2 = SPI mode; 3 = I2C mode. Note To change between modes, the previous mode must be disabled first.
SC1_DATA [0x449E]
15 0-R 0 14 0-R 0 13 0-R 0 12 0-R 0 SC1_DATA 0-RW 7 SC1_DATA 0-RW 6 [7:0] 0-RW 5 0-RW 4 0-RW 3 0-RW 2 0-RW 1 0-RW 0 11 0-R 0 10 0-R 0 9 0-R 0 8 0-R 0
Transmit and receive data register. Writing to this register pushes a byte onto the transmit FIFO. Reading from this register pulls a byte from the receive FIFO.
SC1_UARTPER [0x44B4]
15 0-RW 14 0-RW 13 0-RW 12 0-RW 11 0-RW 10 0-RW 9 0-RW 8 0-RW
SC1_UARTPER SC1_UARTPER 0-RW 7 SC1_UARTPER 0-RW 6 [15:0] 0-RW 5 0-RW 4 0-RW 3 0-RW 2 0-RW 1 0-RW 0
The baud rate period (N) of the clock rate as seen in the equation: 24 MHz Rate = -------------------------------------------2 ( N + ( 0.5 F ) )
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SN250
Functional description--application modules
SC1_UARTFRAC [0x44B6]
15 0-R 0 0 0-R 7 SC1_UARTFRAC 14 0-R 0 0 0-R 6 [0] 13 0-R 0 0 0-R 5 12 0-R 0 0 0-R 4 11 0-R 0 0 0-R 3 10 0-R 0 0 0-R 2 9 0-R 0 0 0-R 1 8 0-R 0 SC1_ UARTFRAC 0-RW 0
The baud rate fractional remainder (F) of the clock rate as derived from the equation: 24 MHz Rate = -------------------------------------------2 ( N + ( 0.5 F ) )
SC1_UARTCFG [0x44AE]
15 0-R 0 0 0-R 7 14 0-R 0 SC1_ UARTAUTO 0-RW 6 [6] 13 0-R 0 SC1_ UARTFLOW 0-RW 5 12 0-R 0 SC1_ UARTODD 0-RW 4 11 0-R 0 SC1_ UARTPAR 0-RW 3 10 0-R 0 SC1_ UART2STP 0-RW 2 9 0-R 0 SC1_ UART8BIT 0-RW 1 8 0-R 0 SC1_ UARTRTS 0-RW 0
SC1_UARTAUTO
Set this bit to enable automatic nRTS assertion by hardware. nRTS will be deasserted when the UART can receive only one more character before the buffer is full. nRTS will be reasserted when the UART can receive more than one character before the buffer is full. The SC1_UARTRTS bit in this register has no effect when this bit is set. Set this bit to enable nRTS/nCTS signals. Clear this bit to disable the signals. When this bit is cleared, the nCTS signal is asserted in hardware to enable the UART transmitter. The GPIO_CFG register should be configured for mode SC1-4A for hardware handshake with nRTS/nCTS and SC1-2 for no handshaking. Clear this bit for even parity. Set this bit for odd parity. Clear this bit for no parity. Set this bit for one parity bit. Clear this bit for one stop bit. Set this bit for two stop bits Clear this bit for seven data bits. Set this bit for eight data bits. RTS is an output signal. When this bit is set, the signal is asserted (== TTL logic 0, GPIO is low, 'XON', RS232 positive voltage), the transmission will proceed. When this bit is cleared, the signal is deasserted (== TTL logic 1, GPIO is high, 'XOFF', RS232 negative voltage), the transmission is inhibited.
SC1_UARTFLOW
[5]
SC1_UARTODD SC1_UARTPAR SC1_UART2STP SC1_UART8BIT SC1_UARTRTS
[4] [3] [2] [1] [0]
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Functional description--application modules
SN250
SC1_UARTSTAT [0x44A4]
15 0-R 0 0 0-R 7 14 0-R 0 SC1_ UARTTXIDLE 1-R 6 13 0-R 0 SC1_ UARTPARERR 0-R 5 12 0-R 0 SC1_ UARTFRMERR 0-R 4 11 0-R 0 SC1_ UARTRXOVF 0-R 3 10 0-R 0 SC1_ UARTTXFREE 0-R 2 9 0-R 0 SC1_ UARTRXVAL 0-R 1 8 0-R 0 SC1_ UARTCTS 0-R 0
SC1_UARTTXIDLE SC1_UARTPARERR SC1_UARTFRMERR SC1_UARTRXOVF SC1_UARTTXFREE SC1_UARTRXVAL SC1_UARTCTS
[6] [5] [4] [3] [2] [1] [0]
This bit is set when the transmit FIFO is empty and the transmitter is idle. This bit is set when the receive FIFO has seen a parity error. This bit clears when the data register (SC1_DATA) is read. This bit is set when the receive FIFO has seen a frame error. This bit clears when the data register (SC1_DATA) is read. This bit is set when the receive FIFO has been overrun. This bit clears when the data register (SC1_DATA) is read. This bit is set when the transmit FIFO is ready to accept at least one byte. This bit is set when the receive FIFO contains at least one byte. This bit shows the current state of the nCTS input signal at the nCTS pin (pin 19, GPIO11). When CTS = 1, the signal is asserted (== TTL logic 0, GPIO is low, 'XON', RS232 positive voltage), the transmission will proceed. When CTS = 0, the signal is deasserted (== TTL logic 1, GPIO is high, 'XOFF', RS232 negative voltage), transmission is inhibited at the end of the current character. Any characters in the transmit buffer will remain there.
SC1_RATELIN [0x44B0]
15 0-R 0 0 0-R 7 SC1_RATELIN 14 0-R 0 0 0-R 6 [3:0] 13 0-R 0 0 0-R 5 12 0-R 0 0 0-R 4 0-RW 3 11 0-R 0 10 0-R 0 9 0-R 0 8 0-R 0
SC1_RATELIN 0-RW 2 0-RW 1 0-RW 0
The linear component (LIN) of the clock rate as seen in the equation: 24 MHz Rate = ------------------------------------------------EXP 2 (LIN + 1) 2
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SN250
Functional description--application modules
SC1_RATEEXP [0x44B2]
15 0-R 0 0 0-R 7 SC1_RATEEXP 14 0-R 0 0 0-R 6 [3:0] 13 0-R 0 0 0-R 5 12 0-R 0 0 0-R 4 0-RW 3 11 0-R 0 10 0-R 0 9 0-R 0 8 0-R 0
SC1_RATEEXP 0-RW 2 0-RW 1 0-RW 0
The exponential component (EXP) of the clock rate as seen in the equation: 24 MHz Rate = ------------------------------------------------EXP 2 (LIN + 1) 2
SC1_SPICFG [0x44AC]
15 0-R 0 0 0-R 7 14 0-R 0 0 0-R 6 13 0-R 0 SC_ SPIRXDRV 0-RW 5 12 0-R 0 SC_SPIMST 0-RW 4 11 0-R 0 S C_SPIRPT 0-RW 3 10 0-R 0 S C_SPIORD 0-RW 2 9 0-R 0 S C_SPIPHA 0-RW 1 8 0-R 0 S C_SPIPOL 0-RW 0
SC_SPIRXDRV
[5]
Receiver-driven mode selection bit (SPI master mode only). Clearing this bit will initiate transactions when transmit data is available. Setting this bit will initiate transactions when the receive buffer (FIFO or DMA) has space. This bit must always be set to put the SPI in master mode (slave mode is not valid). This bit controls behavior on a transmit buffer underrun condition in slave mode. Clearing this bit will send the BUSY token (0xFF) and setting this bit will repeat the last byte. Changing this bit will only take effect when the transmit FIFO is empty and the transmit serializer is idle. Clearing this bit will result in the Most Significant Bit being transmitted first while setting this bit will result in the Least Significant Bit being transmitted first. Clock phase configuration is selected with clearing this bit for sampling on the leading (first edge) and setting this bit for sampling on second edge. Clock polarity configuration is selected with clearing this bit for a rising leading edge and setting this bit for a falling leading edge.
SC_SPIMST SC_SPIRPT
[4] [3]
SC_SPIORD SC_SPIPHA SC_SPIPOL
[2] [1] [0]
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Functional description--application modules
SN250
SC1_SPISTAT [0x44A0]
15 0-R 0 0 0-R 7 SC_SPITXIDLE SC_SPITXFREE SC_SPIRXVAL SC_SPIRXOVF 14 0-R 0 0 0-R 6 [3] [2] [1] [0] 13 0-R 0 0 0-R 5 12 0-R 0 0 0-R 4 11 0-R 0 SC_ SPITXIDLE 0-R 3 10 0-R 0 SC_ SPITXFREE 0-R 2 9 0-R 0 SC_ SPIRXVAL 0-R 1 8 0-R 0 SC_ SPIRXOVF 0-R 0
This bit is set when the transmit FIFO is empty and the transmitter is idle. This bit is set when the transmit FIFO is ready to accept at least one byte. This bit is set when the receive FIFO contains at least one byte. This bit is set when the receive FIFO has been overrun. This bit clears when the data register (SC1_DATA) is read.
SC1_I2CCTRL1 [0x44A6]
15 0-R 0 0 0-R 7 SC_I2CSTOP SC_I2CSTART SC_I2CSEND SC_I2CRECV 14 0-R 0 0 0-R 6 [3] [2] [1] [0] 13 0-R 0 0 0-R 5 12 0-R 0 0 0-R 4 11 0-R 0 SC_ I2CSTOP 0-RW 3 10 0-R 0 SC_ I2CSTART 0-RW 2 9 0-R 0 SC_ I2CSEND 0-RW 1 8 0-R 0 SC_ I2CRECV 0-RW 0
Setting this bit sends the STOP command. It auto clears when the command completes. Setting this bit sends the START or repeated START command. It autoclears when the command completes. Setting this bit transmits a byte. It autoclears when the command completes. Setting this bit receives a byte. It autoclears when the command completes.
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SN250
Functional description--application modules
SC1_I2CCTRL2 [0x44A8]
15 0-R 0 0 0-R 7 SC_I2CACK 14 0-R 0 0 0-R 6 [0] 13 0-R 0 0 0-R 5 12 0-R 0 0 0-R 4 11 0-R 0 0 0-R 3 10 0-R 0 0 0-R 2 9 0-R 0 0 0-R 1 8 0-R 0 SC_I2CACK 0-RW 0
Setting this bit will signal ACK after a received byte. Clearing this bit will signal NACK after a received byte.
SC1_I2CSTAT [0x44A2]
15 0-R 0 0 0-R 7 SC_I2CCMDFIN SC_I2CRXFIN SC_I2CTXFIN SC_I2CRXNAK 14 0-R 0 0 0-R 6 [3] [2] [1] [0] 13 0-R 0 0 0-R 5 12 0-R 0 0 0-R 4 11 0-R 0 SC_ I2CCMDFIN 0-R 3 10 0-R 0 SC_ I2CRXFIN 0-R 2 9 0-R 0 SC_ I2CTXFIN 0-R 1 8 0-R 0 SC_ I2CRXNAK 0-R 0
This bit is set when a START or STOP command completes. It autoclears on next bus activity. This bit is set when a byte is received. It autoclears on next bus activity. This bit is set when a byte is transmitted. It autoclears on next bus activity. This bit is set when a NACK is received from the slave. It autoclears on next bus activity.
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Functional description--application modules
SN250
SC1_DMACTRL [0x4498]
15 0-R 0 0 0-R 7 14 0-R 0 0 0-R 6 13 0-R 0 SC_ TXDMARST 0-W 5 12 0-R 0 SC_ R X DMARST 0-W 4 11 0-R 0 SC_TXLODB 0-RW 3 10 0-R 0 SC_TXLODA 0-RW 2 9 0-R 0 SC _RXLODB 0-RW 1 8 0-R 0 SC_RXLODA 0-RW 0
SC_TXDMARST
[5]
Setting this bit will reset the transmit DMA. The bit is autocleared. Setting this bit will reset the receive DMA. This bit is autocleared. Setting this bit loads DMA transmit buffer B addresses and starts the DMA controller processing transmit buffer B. This bit is autocleared when DMA completes. Writing a zero to this bit will not have any effect. Reading this bit as one indicates DMA processing for buffer B is active or pending. Reading this bit as zero indicates DMA processing for buffer B is complete or idle. Setting this bit loads DMA transmit buffer A addresses and starts the DMA controller processing transmit buffer A. This bit is autocleared when DMA completes. Writing a zero to this bit will not have any effect. Reading this bit as one indicates DMA processing for buffer A is active or pending. Reading this bit as zero indicates DMA processing for buffer A is complete or idle. Setting this bit loads DMA receive buffer B addresses and starts the DMA controller processing receive buffer B. This bit is autocleared when DMA completes. Writing a zero to this bit will not have any effect. Reading this bit as one indicates DMA processing for buffer B is active or pending. Reading this bit as zero indicates DMA processing for buffer B is complete or idle. Setting this bit loads DMA receive buffer A addresses and starts the DMA controller processing receive buffer A. This bit is autocleared when DMA completes. Writing a zero to this bit will not have any effect. Reading this bit as one indicates DMA processing for buffer A is active or pending. Reading this bit as zero indicates DMA processing for buffer A is complete or idle.
SC_RXDMARST [4] SC_TXLODB [3]
SC_TXLODA
[2]
SC_RXLODB
[1]
SC_RXLODA
[0]
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SN250
Functional description--application modules
SC1_DMASTAT [0x4496]
15 0-R 0 SC1 _ RXPARB 0-R 7 14 0-R 0 SC1_ RXPARA 0-R 6 13 0-R 0 SC_RXOVFB 0-R 5 12 0-R 0 SC_RXOVFA 0-R 4 11 0-R 0 SC_TXACTB 0-R 3 10 0-R 0 SC_TXACTA 0-R 2 9 0-R SC1_ RXFRMB SC_RXACTB 0-R 1 8 0-R SC1_ RXFRMA SC_RXACTA 0-R 0
SC1_RXFRMB
[9]
This bit is set when DMA receive buffer B was passed a frame error from the lower hardware FIFO. This bit is autocleared the next time buffer B is loaded or when the receive DMA is reset. This bit is set when DMA receive buffer A was passed a frame error from the lower hardware FIFO. This bit is autocleared the next time buffer A is loaded or when the receive DMA is reset. This bit is set when DMA receive buffer B was passed a parity error from the lower hardware FIFO. This bit is autocleared the next time buffer B is loaded or when the receive DMA is reset. This bit is set when DMA receive buffer A was passed a parity error from the lower hardware FIFO. This bit is autocleared the next time buffer A is loaded or when the receive DMA is reset. This bit is set when DMA receive buffer B was passed an overrun error from the lower hardware FIFO. Neither receive buffers were capable of accepting any more bytes (unloaded), and the FIFO filled up. Buffer B was the next buffer to load, and when it drained the FIFO, the overrun error was passed up to the DMA and flagged with this bit. This bit is autocleared the next time buffer B is loaded or when the receive DMA is reset. This bit is set when DMA receive buffer A was passed an overrun error from the lower hardware FIFO. Neither receive buffers were capable of accepting any more bytes (unloaded), and the FIFO filled up. Buffer A was the next buffer to load, and when it drained the FIFO the overrun error was passed up to the DMA and flagged with this bit. This bit is autocleared the next time buffer A is loaded or when the receive DMA is reset. This bit is set when DMA transmit buffer B is currently active. This bit is set when DMA transmit buffer A is currently active. This bit is set when DMA receive buffer B is currently active. This bit is set when DMA receive buffer A is currently active.
SC1_RXFRMA
[8]
SC1_RXPARB
[7]
SC1_RXPARA
[6]
SC_RXOVFB
[5]
SC_RXOVFA
[4]
SC_TXACTB SC_TXACTA SC_RXACTB SC_RXACTA
[3] [2] [1] [0]
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Functional description--application modules
SN250
SC1_RXCNTA [0x4490]
15 0-R 0 14 0-R 0 13 0-R 0 SC1_RXCNTA 0-R 7 SC1_RXCNTA 0-R 6 [12:0] 0-R 5 0-R 4 0-R 3 0-R 2 0-R 1 0-R 0 12 0-R 11 0-R 10 0-R SC1_RXCNTA 9 0-R 8 0-R
A byte offset (from 0) which points to the location in DMA receive buffer A where the next byte will be placed. When the buffer fills and subsequently unloads, this register wraps around and holds the value zero (pointing back to the first location in the buffer).
SC1_RXCNTB [0x4492]
15 0-R 0 14 0-R 0 13 0-R 0 SC1_RXCNTB 0-R 7 SC1_RXCNTB 0-R 6 [12:0] 0-R 5 0-R 4 0-R 3 0-R 2 0-R 1 0-R 0 12 0-R 11 0-R 10 0-R SC1_RXCNTB 9 0-R 8 0-R
A byte offset (from 0) which points to the location in DMA receive buffer B where the next byte will be placed. When the buffer fills and subsequently unloads, this register wraps around and holds the value zero (pointing back to the first location in the buffer).
SC1_TXCNT [0x4494]
15 0-R 0 14 0-R 0 13 0-R 0 SC1_TXCNT 0-R 7 SC1_TXCNT 0-R 6 [12:0] 0-R 5 0-R 4 0-R 3 0-R 2 0-R 1 0-R 0 12 0-R 11 0-R 10 0-R SC1_TXCNT 9 0-R 8 0-R
A byte offset (from 0) which points to the location in the active (loaded) DMA transmit buffer where the next byte will be placed. When the buffer fills and subsequently unloads, this register wraps around and holds the value zero (pointing back to the first location in the buffer).
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SN250
Functional description--application modules
SC1_RXBEGA [0x4480]
15 0-R 0 14 1-R 1 13 1-R 1 SC1_RXBEGA 0-RW 7 SC1_RXBEGA 0-RW 6 [12:0] 0-RW 5 0-RW 4 0-RW 3 0-RW 2 0-RW 1 0-RW 0 12 0-RW 11 0-RW 10 0-RW SC1_RXBEGA 9 0-RW 8 0-RW
DMA Start address (byte aligned) for receive buffer A.
SC1_RXENDA [0x4482]
15 0-R 0 14 1-R 1 13 1-R 1 SC1_RXENDA 0-RW 7 SC1_RXENDA 0-RW 6 [12:0] 0-RW 5 0-RW 4 0-RW 3 0-RW 2 0-RW 1 0-RW 0 12 0-RW 11 0-RW 10 0-RW SC1_RXENDA 9 0-RW 8 0-RW
DMA End address (byte aligned) for receive buffer A.
SC1_RXBEGB [0x4484]
15 0-R 0 14 1-R 1 13 1-R 1 SC1_RXBEGB 0-RW 7 SC1_RXBEGB 0-RW 6 [12:0] 0-RW 5 0-RW 4 0-RW 3 0-RW 2 0-RW 1 0-RW 0 12 0-RW 11 0-RW 10 0-RW SC1_RXBEGB 9 0-RW 8 0-RW
DMA Start address (byte aligned) for receive buffer B.
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Functional description--application modules
SN250
SC1_RXENDB [0x4486]
15 0-R 0 14 1-R 1 13 1-R 1 SC1_RXENDB 0-RW 7 SC1_RXENDB 0-RW 6 [12:0] 0-RW 5 0-RW 4 0-RW 3 0-RW 2 0-RW 1 0-RW 0 12 0-RW 11 0-RW 10 0-RW SC1_RXENDB 9 0-RW 8 0-RW
DMA End address (byte aligned) for receive buffer B.
SC1_TXBEGA [0x4488]
15 0-R 0 14 1-R 1 13 1-R 1 SC1_TXBEGA 0-RW 7 SC1_TXBEGA 0-RW 6 [12:0] 0-RW 5 0-RW 4 0-RW 3 0-RW 2 0-RW 1 0-RW 0 12 0-RW 11 0-RW 10 0-RW SC1_TXBEGA 9 0-RW 8 0-RW
DMA Start address (byte aligned) for transmit buffer A.
SC1_TXENDA [0x448A]
15 0-R 0 14 1-R 1 13 1-R 1 SC1_TXENDA 0-RW 7 SC1_TXENDA 0-RW 6 [12:0] 0-RW 5 0-RW 4 0-RW 3 0-RW 2 0-RW 1 0-RW 0 12 0-RW 11 0-RW 10 0-RW SC1_TXENDA 9 0-RW 8 0-RW
DMA End address (byte aligned) for transmit buffer A.
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SN250
Functional description--application modules
SC1_TXBEGB [0x448C]
15 0-R 0 14 1-R 1 13 1-R 1 SC1_TXBEGB 0-RW 7 SC1_TXBEGB 0-RW 6 [12:0] 0-RW 5 0-RW 4 0-RW 3 0-RW 2 0-RW 1 0-RW 0 12 0-RW 11 0-RW 10 0-RW SC1_TXBEGB 9 0-RW 8 0-RW
DMA Start address (byte aligned) for transmit buffer B.
SC1_TXENDB [0x448E]
15 0-R 0 14 1-R 1 13 1-R 1 SC1_TXENDB 0-RW 7 SC1_TXENDB 0-RW 6 [12:0] 0-RW 5 0-RW 4 0-RW 3 0-RW 2 0-RW 1 0-RW 0 12 0-RW 11 0-RW 10 0-RW SC1_TXENDB 9 0-RW 8 0-RW
DMA End address (byte aligned) for transmit buffer B.
SC1_RXERRA [0x449A]
15 0-R 0 14 0-R 0 13 0-R 0 SC1_RXERRA 0-R 7 SC1_RXERRA 0-R 6 [12:0] 0-R 5 0-R 4 0-R 3 0-R 2 0-R 1 0-R 0 12 0-R 11 0-R 10 0-R SC1_RXERRA 9 0-R 8 0-R
A byte offset (from 0) which points to the location of the first error in the DMA receive buffer A. If there is no error, it will hold the value zero. This register will not be updated by subsequent errors arriving in the DMA. The next error will only be recorded if the buffer unloads and is reloaded or the receive DMA is reset.
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Functional description--application modules
SN250
SC1_RXERRB [0x449C]
15 0-R 0 14 0-R 0 13 0-R 0 SC1_RXERRB 0-R 7 SC1_RXERRB 0-R 6 [12:0] 0-R 5 0-R 4 0-R 3 0-R 2 0-R 1 0-R 0 12 0-R 11 0-R 10 0-R SC1_RXERRB 9 0-R 8 0-R
A byte offset (from 0) which points to the location of the first error in the DMA receive buffer B. If there is no error, it will hold the value zero. This register will not be updated by subsequent errors arriving in the DMA. The next error will only be recorded if the buffer unloads and is reloaded or the receive DMA is reset.
INT_SC1CFG [0x4624]
15 0-R 0 INT_ SCCMDFIN 0-RW 7 14 0-RW INT_ SC1PARERR INT_ SCTXFIN 0-RW 6 13 0-RW INT_ SC1FR M ERR INT_ S C R X F IN 0-RW 5 12 0-RW INT_ SC TXULDB INT_ SCTXUND 0-RW 4 11 0-RW INT_ SCTXULDA INT_ SCRXOVF 0-RW 3 10 0-RW INT_ SCRXULDB INT_ SCTXIDL E 0-RW 2 9 0-RW INT_ SCRXULDA INT_ SCTXFR EE 0-RW 1 8 0-RW I N T _S C N A K INT_ SCRXVAL 0-RW 0
INT_SC1PARERR
[14]
Parity error received (UART) interrupt enable. Frame error received (UART) interrupt enable. DMA Tx buffer B unloaded interrupt enable. DMA Tx buffer A unloaded interrupt enable. DMA Rx buffer B unloaded interrupt enable. DMA Rx buffer A unloaded interrupt enable. Nack received (I2C) interrupt enable. START/STOP command complete (I2C) interrupt enable. Transmit operation complete (I2C) interrupt enable. Receive operation complete (I2C) interrupt enable. Transmit buffer underrun interrupt enable. Receive buffer overrun interrupt enable. Transmitter idle interrupt enable. Transmit buffer free interrupt enable. Receive buffer has data interrupt enable.
INT_SC1FRMERR [13] INT_SCTXULDB INT_SCTXULDA INT_SCRXULDB INT_SCRXULDA INT_SCNAK INT_SCCMDFIN INT_SCTXFIN INT_SCRXFIN INT_SCTXUND INT_SCRXOVF INT_SCTXIDLE INT_SCTXFREE INT_SCRXVAL [12] [11] [10] [9] [8] [7] [6] [5] [4] [3] [2] [1] [0]
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SN250
Functional description--application modules
INT_SC1FLAG [0x460C]
15 0-R 0 INT_ SCCMDFIN 0-RW 7 14 0-RW INT_ SC1PARERR INT_ SCTXFIN 0-RW 6 13 0-RW INT_ SC1FRMERR INT_ SC RXFIN 0-RW 5 12 0-RW INT_ SCTXU L DB INT_ SCT X UND 0-RW 4 11 0-RW INT_ SCTXULDA INT_ SCRXOVF 0-RW 3 10 0-RW INT_ S C R X U LD B INT_ SCTXIDLE 0-RW 2 9 0-RW INT_ SCRXULDA INT_ SCTXFREE 0-RW 1 8 0-RW INT_SCN A K INT_ SCRXVAL 0-RW 0
INT_SC1PARERR
[14]
Parity error received (UART) interrupt pending. Frame error received (UART) interrupt pending. DMA Tx buffer B unloaded interrupt pending. DMA Tx buffer A unloaded interrupt pending. DMA Rx buffer B unloaded interrupt pending. DMA Rx buffer A unloaded interrupt pending. Nack received (I2C) interrupt pending. START/STOP command complete (I2C) interrupt pending. Transmit operation complete (I2C) interrupt pending. Receive operation complete (I2C) interrupt pending. Transmit buffer underrun interrupt pending. Receive buffer overrun interrupt pending. Transmitter idle interrupt pending. Transmit buffer free interrupt pending. Receive buffer has data interrupt pending.
INT_SC1FRMERR [13] INT_SCTXULDB INT_SCTXULDA INT_SCRXULDB INT_SCRXULDA INT_SCNAK INT_SCCMDFIN INT_SCTXFIN INT_SCRXFIN INT_SCTXUND INT_SCRXOVF INT_SCTXIDLE INT_SCTXFREE INT_SCRXVAL [12] [11] [10] [9] [8] [7] [6] [5] [4] [3] [2] [1] [0]
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Functional description--application modules
SN250
7.3
Serial controller SC2
The SN250 SC2 module provides synchronous (SPI or I2C) serial communications. Figure 8 is a block diagram of the SC2 module. Figure 8. SC2 block diagram
The full-duplex interface of the SC2 module can be configured into one of these two communication modes, but it cannot run them simultaneously. To reduce the interrupt service requirements of the CPU, the SC2 module contains buffered data management schemes. A dedicated, buffered DMA controller is available to the SPI while a FIFO is available to both modes. In addition, a SC2 data register allows the software application direct access to the SC2 data. Finally, the SC2 routes the interface signals to GPIO pins. These are shared with other functions and are controlled by the GPIO_CFG register. For selecting alternate pin-functions, please refer to Table 17 and Table 18.
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SN250
Functional description--application modules
7.3.1
SPI modes
The SPI mode of the SC2 supports both master and slave modes. It has a fixed word length of 8 bits. The SC2 SPI controller is enabled with SC2_MODE set to 2. The SC2 SPI mode has the following features:
Master and slave modes Full duplex operation Programmable master mode clock frequency (12MHz max.) Slave mode up to 5MHz bit rate Programmable clock polarity and clock phase Selectable data shift direction (either LSB or MSB first) Optional slave select input MOSI (master out/slave in) MISO (master in/slave out) MSCLK (serial clock) nSSEL (slave select--only in slave mode)
The following signals can be made available on the GPIO pins:
SPI master mode
The SC2 SPI Master controller is enabled with the SC_SPIMST set in the SC2_SPICFG register. The SC2 SPI module obtains its reference clock from a programmable clock generator. Clock rates are set by a clock division ratio from the 24 MHz clock:
24 MHz Rate = ------------------------------------------------EXP 2 (LIN + 1 ) 2
EXP is written to the SC2_RATEEXP register and LIN to the SC2_RATELIN register. Since the range for both values is 0 to 15, the fastest data rate is 12Mbps and the slowest is 22.9bps. The SC2 SPI Master supports various frame formats depending upon the clock polarity (SC_SPIPOL), clock phase (SC_SPIPHA), and direction of data (SC_SPIORD) (see Table 24). The register bits SC_SPIPOL, SC_SPIPHA, and SC_SPIORD are defined within the SC2_SPICFG register. Note: Switching the SPI configuration from SC_SPIPOL=1 to SC_SPIPOL=0 without subsequently setting SC2_MODE=0 and reinitializing the SPI will cause an extra byte (0xFE) to be transmitted immediately before the first intended byte.
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Functional description--application modules Table 24. SC2 SPI master mode formats
GPIO_CFG[7:4]
SN250
SC2_SPICFG SC_SPIORD SC_SPIPHA SC_SPIMST SC_SPIPOL SC2_MODE
Frame Format
2
1
0
0
0
SC2-3M mode
2
1
0
0
1
SC2-3M mode
2
1
0
1
0
SC2-3M mode
2
1
0
1
1
SC2-3M mode SC2-3M mode SC2-4S mode SC2-2 mode
2 2 2
1 1 1
1 -
-
-
Same as above except LSB first instead of MSB first Illegal Illegal
Serialized SC2 SPI transmit data is driven to the output pin MOSI. SC2 SPI master data is received from the input pin MISO. To generate slave select signals to SPI slave devices, other GPIO pins have to be used and their assertion must be controlled by software. Characters transmitted and received are passed through transmit and receive FIFOs. The transmit and receive FIFOs are 4 bytes deep. These FIFOs are accessed under software control by accessing the SC2_DATA data register or under hardware control using a DMA controller. When a transmit character is written to the (empty) transmit FIFO, the register bit SC_SPITXIDLE in the SC2_SPISTAT register clears and indicates that not all characters are transmitted yet. Further transmit characters can be wr |
