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636 lines
18 KiB
C
Executable File
636 lines
18 KiB
C
Executable File
/*! \file i2c.c \brief I2C interface using AVR Two-Wire Interface (TWI) hardware. */
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//*****************************************************************************
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//
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// File Name : 'i2c.c'
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// Title : I2C interface using AVR Two-Wire Interface (TWI) hardware
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// Author : Pascal Stang - Copyright (C) 2002-2003
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// Created : 2002.06.25
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// Revised : 2003.03.02
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// Version : 0.9
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// Target MCU : Atmel AVR series
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// Editor Tabs : 4
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//
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// Description : I2C (pronounced "eye-squared-see") is a two-wire bidirectional
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// network designed for easy transfer of information between a wide variety
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// of intelligent devices. Many of the Atmel AVR series processors have
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// hardware support for transmitting and receiving using an I2C-type bus.
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// In addition to the AVRs, there are thousands of other parts made by
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// manufacturers like Philips, Maxim, National, TI, etc that use I2C as
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// their primary means of communication and control. Common device types
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// are A/D & D/A converters, temp sensors, intelligent battery monitors,
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// MP3 decoder chips, EEPROM chips, multiplexing switches, etc.
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//
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// I2C uses only two wires (SDA and SCL) to communicate bidirectionally
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// between devices. I2C is a multidrop network, meaning that you can have
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// several devices on a single bus. Because I2C uses a 7-bit number to
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// identify which device it wants to talk to, you cannot have more than
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// 127 devices on a single bus.
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//
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// I2C ordinarily requires two 4.7K pull-up resistors to power (one each on
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// SDA and SCL), but for small numbers of devices (maybe 1-4), it is enough
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// to activate the internal pull-up resistors in the AVR processor. To do
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// this, set the port pins, which correspond to the I2C pins SDA/SCL, high.
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// For example, on the mega163, sbi(PORTC, 0); sbi(PORTC, 1);.
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//
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// For complete information about I2C, see the Philips Semiconductor
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// website. They created I2C and have the largest family of devices that
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// work with I2C.
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//
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// Note: Many manufacturers market I2C bus devices under a different or generic
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// bus name like "Two-Wire Interface". This is because Philips still holds
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// "I2C" as a trademark. For example, SMBus and SMBus devices are hardware
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// compatible and closely related to I2C. They can be directly connected
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// to an I2C bus along with other I2C devices are are generally accessed in
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// the same way as I2C devices. SMBus is often found on modern motherboards
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// for temp sensing and other low-level control tasks.
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//
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// This code is distributed under the GNU Public License
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// which can be found at http://www.gnu.org/licenses/gpl.txt
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//
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//*****************************************************************************
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#include <avr/io.h>
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#include <avr/signal.h>
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#include <avr/interrupt.h>
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#include "i2c.h"
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#include "rprintf.h" // include printf function library
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#include "uart2.h"
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// Standard I2C bit rates are:
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// 100KHz for slow speed
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// 400KHz for high speed
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//#define I2C_DEBUG
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// I2C state and address variables
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static volatile eI2cStateType I2cState;
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static u08 I2cDeviceAddrRW;
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// send/transmit buffer (outgoing data)
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static u08 I2cSendData[I2C_SEND_DATA_BUFFER_SIZE];
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static u08 I2cSendDataIndex;
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static u08 I2cSendDataLength;
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// receive buffer (incoming data)
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static u08 I2cReceiveData[I2C_RECEIVE_DATA_BUFFER_SIZE];
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static u08 I2cReceiveDataIndex;
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static u08 I2cReceiveDataLength;
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// function pointer to i2c receive routine
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//! I2cSlaveReceive is called when this processor
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// is addressed as a slave for writing
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static void (*i2cSlaveReceive)(u08 receiveDataLength, u08* recieveData);
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//! I2cSlaveTransmit is called when this processor
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// is addressed as a slave for reading
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static u08 (*i2cSlaveTransmit)(u08 transmitDataLengthMax, u08* transmitData);
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// functions
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void i2cInit(void)
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{
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// set pull-up resistors on I2C bus pins
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// TODO: should #ifdef these
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sbi(PORTC, 0); // i2c SCL on ATmega163,323,16,32,etc
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sbi(PORTC, 1); // i2c SDA on ATmega163,323,16,32,etc
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sbi(PORTD, 0); // i2c SCL on ATmega128,64
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sbi(PORTD, 1); // i2c SDA on ATmega128,64
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// clear SlaveReceive and SlaveTransmit handler to null
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i2cSlaveReceive = 0;
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i2cSlaveTransmit = 0;
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// set i2c bit rate to 100KHz
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i2cSetBitrate(100);
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// enable TWI (two-wire interface)
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sbi(TWCR, TWEN);
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// set state
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I2cState = I2C_IDLE;
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// enable TWI interrupt and slave address ACK
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sbi(TWCR, TWIE);
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sbi(TWCR, TWEA);
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//outb(TWCR, (inb(TWCR)&TWCR_CMD_MASK)|BV(TWINT)|BV(TWEA));
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// enable interrupts
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sei();
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}
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void i2cSetBitrate(u16 bitrateKHz)
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{
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u08 bitrate_div;
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// set i2c bitrate
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// SCL freq = F_CPU/(16+2*TWBR))
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#ifdef TWPS0
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// for processors with additional bitrate division (mega128)
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// SCL freq = F_CPU/(16+2*TWBR*4^TWPS)
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// set TWPS to zero
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cbi(TWSR, TWPS0);
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cbi(TWSR, TWPS1);
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#endif
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// calculate bitrate division
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bitrate_div = ((F_CPU/1000l)/bitrateKHz);
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if(bitrate_div >= 16)
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bitrate_div = (bitrate_div-16)/2;
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outb(TWBR, bitrate_div);
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}
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void i2cSetLocalDeviceAddr(u08 deviceAddr, u08 genCallEn)
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{
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// set local device address (used in slave mode only)
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outb(TWAR, ((deviceAddr&0xFE) | (genCallEn?1:0)) );
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}
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void i2cSetSlaveReceiveHandler(void (*i2cSlaveRx_func)(u08 receiveDataLength, u08* recieveData))
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{
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i2cSlaveReceive = i2cSlaveRx_func;
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}
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void i2cSetSlaveTransmitHandler(u08 (*i2cSlaveTx_func)(u08 transmitDataLengthMax, u08* transmitData))
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{
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i2cSlaveTransmit = i2cSlaveTx_func;
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}
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inline void i2cSendStart(void)
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{
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// send start condition
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outb(TWCR, (inb(TWCR)&TWCR_CMD_MASK)|BV(TWINT)|BV(TWSTA));
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}
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inline void i2cSendStop(void)
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{
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// transmit stop condition
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// leave with TWEA on for slave receiving
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outb(TWCR, (inb(TWCR)&TWCR_CMD_MASK)|BV(TWINT)|BV(TWEA)|BV(TWSTO));
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}
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inline void i2cWaitForComplete(void)
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{
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// wait for i2c interface to complete operation
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while( !(inb(TWCR) & BV(TWINT)) );
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}
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inline void i2cSendByte(u08 data)
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{
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// save data to the TWDR
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outb(TWDR, data);
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// begin send
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outb(TWCR, (inb(TWCR)&TWCR_CMD_MASK)|BV(TWINT));
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}
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inline void i2cReceiveByte(u08 ackFlag)
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{
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// begin receive over i2c
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if( ackFlag )
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{
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// ackFlag = TRUE: ACK the recevied data
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outb(TWCR, (inb(TWCR)&TWCR_CMD_MASK)|BV(TWINT)|BV(TWEA));
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}
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else
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{
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// ackFlag = FALSE: NACK the recevied data
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outb(TWCR, (inb(TWCR)&TWCR_CMD_MASK)|BV(TWINT));
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}
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}
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inline u08 i2cGetReceivedByte(void)
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{
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// retieve received data byte from i2c TWDR
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return( inb(TWDR) );
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}
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inline u08 i2cGetStatus(void)
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{
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// retieve current i2c status from i2c TWSR
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return( inb(TWSR) );
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}
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void i2cMasterSend(u08 deviceAddr, u08 length, u08* data)
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{
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u08 i;
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// wait for interface to be ready
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while(I2cState);
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// set state
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I2cState = I2C_MASTER_TX;
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// save data
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I2cDeviceAddrRW = (deviceAddr & 0xFE); // RW cleared: write operation
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for(i=0; i<length; i++)
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I2cSendData[i] = *data++;
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I2cSendDataIndex = 0;
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I2cSendDataLength = length;
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// send start condition
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i2cSendStart();
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}
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void i2cMasterReceive(u08 deviceAddr, u08 length, u08* data)
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{
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u08 i;
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// wait for interface to be ready
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while(I2cState);
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// set state
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I2cState = I2C_MASTER_RX;
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// save data
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I2cDeviceAddrRW = (deviceAddr|0x01); // RW set: read operation
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I2cReceiveDataIndex = 0;
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I2cReceiveDataLength = length;
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// send start condition
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i2cSendStart();
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// wait for data
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while(I2cState);
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// return data
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for(i=0; i<length; i++)
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*data++ = I2cReceiveData[i];
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}
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u08 i2cMasterSendNI(u08 deviceAddr, u08 length, u08* data)
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{
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u08 retval = I2C_OK;
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// disable TWI interrupt
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cbi(TWCR, TWIE);
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// send start condition
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i2cSendStart();
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i2cWaitForComplete();
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// send device address with write
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i2cSendByte( deviceAddr & 0xFE );
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i2cWaitForComplete();
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// check if device is present and live
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if( inb(TWSR) == TW_MT_SLA_ACK)
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{
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// send data
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while(length)
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{
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i2cSendByte( *data++ );
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i2cWaitForComplete();
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length--;
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}
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}
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else
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{
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// device did not ACK it's address,
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// data will not be transferred
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// return error
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retval = I2C_ERROR_NODEV;
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}
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// transmit stop condition
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// leave with TWEA on for slave receiving
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i2cSendStop();
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while( !(inb(TWCR) & BV(TWSTO)) );
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// enable TWI interrupt
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sbi(TWCR, TWIE);
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return retval;
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}
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u08 i2cMasterReceiveNI(u08 deviceAddr, u08 length, u08 *data)
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{
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u08 retval = I2C_OK;
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// disable TWI interrupt
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cbi(TWCR, TWIE);
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// send start condition
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i2cSendStart();
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i2cWaitForComplete();
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// send device address with read
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i2cSendByte( deviceAddr | 0x01 );
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i2cWaitForComplete();
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// check if device is present and live
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if( inb(TWSR) == TW_MR_SLA_ACK)
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{
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// accept receive data and ack it
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while(length > 1)
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{
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i2cReceiveByte(TRUE);
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i2cWaitForComplete();
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*data++ = i2cGetReceivedByte();
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// decrement length
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length--;
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}
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// accept receive data and nack it (last-byte signal)
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i2cReceiveByte(FALSE);
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i2cWaitForComplete();
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*data++ = i2cGetReceivedByte();
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}
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else
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{
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// device did not ACK it's address,
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// data will not be transferred
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// return error
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retval = I2C_ERROR_NODEV;
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}
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// transmit stop condition
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// leave with TWEA on for slave receiving
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i2cSendStop();
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// enable TWI interrupt
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sbi(TWCR, TWIE);
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return retval;
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}
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/*
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void i2cMasterTransferNI(u08 deviceAddr, u08 sendlength, u08* senddata, u08 receivelength, u08* receivedata)
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{
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// disable TWI interrupt
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cbi(TWCR, TWIE);
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// send start condition
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i2cSendStart();
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i2cWaitForComplete();
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// if there's data to be sent, do it
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if(sendlength)
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{
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// send device address with write
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i2cSendByte( deviceAddr & 0xFE );
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i2cWaitForComplete();
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// send data
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while(sendlength)
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{
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i2cSendByte( *senddata++ );
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i2cWaitForComplete();
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sendlength--;
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}
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}
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// if there's data to be received, do it
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if(receivelength)
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{
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// send repeated start condition
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i2cSendStart();
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i2cWaitForComplete();
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// send device address with read
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i2cSendByte( deviceAddr | 0x01 );
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i2cWaitForComplete();
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// accept receive data and ack it
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while(receivelength > 1)
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{
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i2cReceiveByte(TRUE);
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i2cWaitForComplete();
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*receivedata++ = i2cGetReceivedByte();
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// decrement length
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receivelength--;
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}
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// accept receive data and nack it (last-byte signal)
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i2cReceiveByte(TRUE);
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i2cWaitForComplete();
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*receivedata++ = i2cGetReceivedByte();
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}
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// transmit stop condition
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// leave with TWEA on for slave receiving
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i2cSendStop();
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while( !(inb(TWCR) & BV(TWSTO)) );
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// enable TWI interrupt
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sbi(TWCR, TWIE);
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}
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*/
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//! I2C (TWI) interrupt service routine
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SIGNAL(SIG_2WIRE_SERIAL)
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{
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// read status bits
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u08 status = inb(TWSR) & TWSR_STATUS_MASK;
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switch(status)
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{
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// Master General
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case TW_START: // 0x08: Sent start condition
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case TW_REP_START: // 0x10: Sent repeated start condition
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#ifdef I2C_DEBUG
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rprintfInit(uart1AddToTxBuffer);
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rprintf("I2C: M->START\r\n");
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rprintfInit(uart1SendByte);
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#endif
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// send device address
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i2cSendByte(I2cDeviceAddrRW);
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break;
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// Master Transmitter & Receiver status codes
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case TW_MT_SLA_ACK: // 0x18: Slave address acknowledged
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case TW_MT_DATA_ACK: // 0x28: Data acknowledged
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#ifdef I2C_DEBUG
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rprintfInit(uart1AddToTxBuffer);
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rprintf("I2C: MT->SLA_ACK or DATA_ACK\r\n");
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rprintfInit(uart1SendByte);
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#endif
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if(I2cSendDataIndex < I2cSendDataLength)
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{
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// send data
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i2cSendByte( I2cSendData[I2cSendDataIndex++] );
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}
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else
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{
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// transmit stop condition, enable SLA ACK
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i2cSendStop();
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// set state
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I2cState = I2C_IDLE;
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}
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break;
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case TW_MR_DATA_NACK: // 0x58: Data received, NACK reply issued
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#ifdef I2C_DEBUG
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rprintfInit(uart1AddToTxBuffer);
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rprintf("I2C: MR->DATA_NACK\r\n");
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rprintfInit(uart1SendByte);
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#endif
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// store final received data byte
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I2cReceiveData[I2cReceiveDataIndex++] = inb(TWDR);
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// continue to transmit STOP condition
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case TW_MR_SLA_NACK: // 0x48: Slave address not acknowledged
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case TW_MT_SLA_NACK: // 0x20: Slave address not acknowledged
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case TW_MT_DATA_NACK: // 0x30: Data not acknowledged
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#ifdef I2C_DEBUG
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rprintfInit(uart1AddToTxBuffer);
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rprintf("I2C: MTR->SLA_NACK or MT->DATA_NACK\r\n");
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rprintfInit(uart1SendByte);
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#endif
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// transmit stop condition, enable SLA ACK
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i2cSendStop();
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// set state
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I2cState = I2C_IDLE;
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break;
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case TW_MT_ARB_LOST: // 0x38: Bus arbitration lost
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//case TW_MR_ARB_LOST: // 0x38: Bus arbitration lost
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#ifdef I2C_DEBUG
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rprintfInit(uart1AddToTxBuffer);
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rprintf("I2C: MT->ARB_LOST\r\n");
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rprintfInit(uart1SendByte);
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#endif
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// release bus
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outb(TWCR, (inb(TWCR)&TWCR_CMD_MASK)|BV(TWINT));
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// set state
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I2cState = I2C_IDLE;
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// release bus and transmit start when bus is free
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//outb(TWCR, (inb(TWCR)&TWCR_CMD_MASK)|BV(TWINT)|BV(TWSTA));
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break;
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case TW_MR_DATA_ACK: // 0x50: Data acknowledged
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#ifdef I2C_DEBUG
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rprintfInit(uart1AddToTxBuffer);
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rprintf("I2C: MR->DATA_ACK\r\n");
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rprintfInit(uart1SendByte);
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#endif
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// store received data byte
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I2cReceiveData[I2cReceiveDataIndex++] = inb(TWDR);
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// fall-through to see if more bytes will be received
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case TW_MR_SLA_ACK: // 0x40: Slave address acknowledged
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#ifdef I2C_DEBUG
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rprintfInit(uart1AddToTxBuffer);
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rprintf("I2C: MR->SLA_ACK\r\n");
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rprintfInit(uart1SendByte);
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#endif
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if(I2cReceiveDataIndex < (I2cReceiveDataLength-1))
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// data byte will be received, reply with ACK (more bytes in transfer)
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i2cReceiveByte(TRUE);
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else
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// data byte will be received, reply with NACK (final byte in transfer)
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i2cReceiveByte(FALSE);
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break;
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// Slave Receiver status codes
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case TW_SR_SLA_ACK: // 0x60: own SLA+W has been received, ACK has been returned
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case TW_SR_ARB_LOST_SLA_ACK: // 0x68: own SLA+W has been received, ACK has been returned
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case TW_SR_GCALL_ACK: // 0x70: GCA+W has been received, ACK has been returned
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case TW_SR_ARB_LOST_GCALL_ACK: // 0x78: GCA+W has been received, ACK has been returned
|
|
#ifdef I2C_DEBUG
|
|
rprintfInit(uart1AddToTxBuffer);
|
|
rprintf("I2C: SR->SLA_ACK\r\n");
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|
rprintfInit(uart1SendByte);
|
|
#endif
|
|
// we are being addressed as slave for writing (data will be received from master)
|
|
// set state
|
|
I2cState = I2C_SLAVE_RX;
|
|
// prepare buffer
|
|
I2cReceiveDataIndex = 0;
|
|
// receive data byte and return ACK
|
|
outb(TWCR, (inb(TWCR)&TWCR_CMD_MASK)|BV(TWINT)|BV(TWEA));
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|
break;
|
|
case TW_SR_DATA_ACK: // 0x80: data byte has been received, ACK has been returned
|
|
case TW_SR_GCALL_DATA_ACK: // 0x90: data byte has been received, ACK has been returned
|
|
#ifdef I2C_DEBUG
|
|
rprintfInit(uart1AddToTxBuffer);
|
|
rprintf("I2C: SR->DATA_ACK\r\n");
|
|
rprintfInit(uart1SendByte);
|
|
#endif
|
|
// get previously received data byte
|
|
I2cReceiveData[I2cReceiveDataIndex++] = inb(TWDR);
|
|
// check receive buffer status
|
|
if(I2cReceiveDataIndex < I2C_RECEIVE_DATA_BUFFER_SIZE)
|
|
{
|
|
// receive data byte and return ACK
|
|
i2cReceiveByte(TRUE);
|
|
//outb(TWCR, (inb(TWCR)&TWCR_CMD_MASK)|BV(TWINT)|BV(TWEA));
|
|
}
|
|
else
|
|
{
|
|
// receive data byte and return NACK
|
|
i2cReceiveByte(FALSE);
|
|
//outb(TWCR, (inb(TWCR)&TWCR_CMD_MASK)|BV(TWINT));
|
|
}
|
|
break;
|
|
case TW_SR_DATA_NACK: // 0x88: data byte has been received, NACK has been returned
|
|
case TW_SR_GCALL_DATA_NACK: // 0x98: data byte has been received, NACK has been returned
|
|
#ifdef I2C_DEBUG
|
|
rprintfInit(uart1AddToTxBuffer);
|
|
rprintf("I2C: SR->DATA_NACK\r\n");
|
|
rprintfInit(uart1SendByte);
|
|
#endif
|
|
// receive data byte and return NACK
|
|
i2cReceiveByte(FALSE);
|
|
//outb(TWCR, (inb(TWCR)&TWCR_CMD_MASK)|BV(TWINT));
|
|
break;
|
|
case TW_SR_STOP: // 0xA0: STOP or REPEATED START has been received while addressed as slave
|
|
#ifdef I2C_DEBUG
|
|
rprintfInit(uart1AddToTxBuffer);
|
|
rprintf("I2C: SR->SR_STOP\r\n");
|
|
rprintfInit(uart1SendByte);
|
|
#endif
|
|
// switch to SR mode with SLA ACK
|
|
outb(TWCR, (inb(TWCR)&TWCR_CMD_MASK)|BV(TWINT)|BV(TWEA));
|
|
// i2c receive is complete, call i2cSlaveReceive
|
|
if(i2cSlaveReceive) i2cSlaveReceive(I2cReceiveDataIndex, I2cReceiveData);
|
|
// set state
|
|
I2cState = I2C_IDLE;
|
|
break;
|
|
|
|
// Slave Transmitter
|
|
case TW_ST_SLA_ACK: // 0xA8: own SLA+R has been received, ACK has been returned
|
|
case TW_ST_ARB_LOST_SLA_ACK: // 0xB0: GCA+R has been received, ACK has been returned
|
|
#ifdef I2C_DEBUG
|
|
rprintfInit(uart1AddToTxBuffer);
|
|
rprintf("I2C: ST->SLA_ACK\r\n");
|
|
rprintfInit(uart1SendByte);
|
|
#endif
|
|
// we are being addressed as slave for reading (data must be transmitted back to master)
|
|
// set state
|
|
I2cState = I2C_SLAVE_TX;
|
|
// request data from application
|
|
if(i2cSlaveTransmit) I2cSendDataLength = i2cSlaveTransmit(I2C_SEND_DATA_BUFFER_SIZE, I2cSendData);
|
|
// reset data index
|
|
I2cSendDataIndex = 0;
|
|
// fall-through to transmit first data byte
|
|
case TW_ST_DATA_ACK: // 0xB8: data byte has been transmitted, ACK has been received
|
|
#ifdef I2C_DEBUG
|
|
rprintfInit(uart1AddToTxBuffer);
|
|
rprintf("I2C: ST->DATA_ACK\r\n");
|
|
rprintfInit(uart1SendByte);
|
|
#endif
|
|
// transmit data byte
|
|
outb(TWDR, I2cSendData[I2cSendDataIndex++]);
|
|
if(I2cSendDataIndex < I2cSendDataLength)
|
|
// expect ACK to data byte
|
|
outb(TWCR, (inb(TWCR)&TWCR_CMD_MASK)|BV(TWINT)|BV(TWEA));
|
|
else
|
|
// expect NACK to data byte
|
|
outb(TWCR, (inb(TWCR)&TWCR_CMD_MASK)|BV(TWINT));
|
|
break;
|
|
case TW_ST_DATA_NACK: // 0xC0: data byte has been transmitted, NACK has been received
|
|
case TW_ST_LAST_DATA: // 0xC8:
|
|
#ifdef I2C_DEBUG
|
|
rprintfInit(uart1AddToTxBuffer);
|
|
rprintf("I2C: ST->DATA_NACK or LAST_DATA\r\n");
|
|
rprintfInit(uart1SendByte);
|
|
#endif
|
|
// all done
|
|
// switch to open slave
|
|
outb(TWCR, (inb(TWCR)&TWCR_CMD_MASK)|BV(TWINT)|BV(TWEA));
|
|
// set state
|
|
I2cState = I2C_IDLE;
|
|
break;
|
|
|
|
// Misc
|
|
case TW_NO_INFO: // 0xF8: No relevant state information
|
|
// do nothing
|
|
#ifdef I2C_DEBUG
|
|
rprintfInit(uart1AddToTxBuffer);
|
|
rprintf("I2C: NO_INFO\r\n");
|
|
rprintfInit(uart1SendByte);
|
|
#endif
|
|
break;
|
|
case TW_BUS_ERROR: // 0x00: Bus error due to illegal start or stop condition
|
|
#ifdef I2C_DEBUG
|
|
rprintfInit(uart1AddToTxBuffer);
|
|
rprintf("I2C: BUS_ERROR\r\n");
|
|
rprintfInit(uart1SendByte);
|
|
#endif
|
|
// reset internal hardware and release bus
|
|
outb(TWCR, (inb(TWCR)&TWCR_CMD_MASK)|BV(TWINT)|BV(TWSTO)|BV(TWEA));
|
|
// set state
|
|
I2cState = I2C_IDLE;
|
|
break;
|
|
}
|
|
}
|
|
|
|
eI2cStateType i2cGetState(void)
|
|
{
|
|
return I2cState;
|
|
}
|