Refactor use of legacy i2c implementation (#14341)
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#ifndef _I2CMASTER_H |
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#define _I2CMASTER_H 1 |
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/*************************************************************************
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* Title: C include file for the I2C master interface
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* (i2cmaster.S or twimaster.c) |
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* Author: Peter Fleury <pfleury@gmx.ch> http://jump.to/fleury
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* File: $Id: i2cmaster.h,v 1.10 2005/03/06 22:39:57 Peter Exp $ |
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* Software: AVR-GCC 3.4.3 / avr-libc 1.2.3 |
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* Target: any AVR device |
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* Usage: see Doxygen manual |
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**************************************************************************/ |
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#ifdef DOXYGEN |
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/**
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@defgroup pfleury_ic2master I2C Master library |
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@code #include <i2cmaster.h> @endcode |
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@brief I2C (TWI) Master Software Library |
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Basic routines for communicating with I2C slave devices. This single master
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implementation is limited to one bus master on the I2C bus.
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This I2c library is implemented as a compact assembler software implementation of the I2C protocol
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which runs on any AVR (i2cmaster.S) and as a TWI hardware interface for all AVR with built-in TWI hardware (twimaster.c). |
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Since the API for these two implementations is exactly the same, an application can be linked either against the |
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software I2C implementation or the hardware I2C implementation. |
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Use 4.7k pull-up resistor on the SDA and SCL pin. |
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Adapt the SCL and SDA port and pin definitions and eventually the delay routine in the module
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i2cmaster.S to your target when using the software I2C implementation !
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Adjust the CPU clock frequence F_CPU in twimaster.c or in the Makfile when using the TWI hardware implementaion. |
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@note
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The module i2cmaster.S is based on the Atmel Application Note AVR300, corrected and adapted
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to GNU assembler and AVR-GCC C call interface. |
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Replaced the incorrect quarter period delays found in AVR300 with
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half period delays.
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@author Peter Fleury pfleury@gmx.ch http://jump.to/fleury
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@par API Usage Example |
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The following code shows typical usage of this library, see example test_i2cmaster.c |
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@code |
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#include <i2cmaster.h> |
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#define Dev24C02 0xA2 // device address of EEPROM 24C02, see datasheet
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int main(void) |
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{ |
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unsigned char ret; |
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i2c_init(); // initialize I2C library
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// write 0x75 to EEPROM address 5 (Byte Write)
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i2c_start_wait(Dev24C02+I2C_WRITE); // set device address and write mode
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i2c_write(0x05); // write address = 5
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i2c_write(0x75); // write value 0x75 to EEPROM
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i2c_stop(); // set stop conditon = release bus
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// read previously written value back from EEPROM address 5
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i2c_start_wait(Dev24C02+I2C_WRITE); // set device address and write mode
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i2c_write(0x05); // write address = 5
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i2c_rep_start(Dev24C02+I2C_READ); // set device address and read mode
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ret = i2c_readNak(); // read one byte from EEPROM
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i2c_stop(); |
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for(;;); |
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} |
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@endcode |
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*/ |
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#endif /* DOXYGEN */ |
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/**@{*/ |
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#if (__GNUC__ * 100 + __GNUC_MINOR__) < 304 |
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#error "This library requires AVR-GCC 3.4 or later, update to newer AVR-GCC compiler !" |
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#endif |
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#include <avr/io.h> |
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/** defines the data direction (reading from I2C device) in i2c_start(),i2c_rep_start() */ |
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#define I2C_READ 1 |
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/** defines the data direction (writing to I2C device) in i2c_start(),i2c_rep_start() */ |
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#define I2C_WRITE 0 |
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/**
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@brief initialize the I2C master interace. Need to be called only once
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@param void |
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@return none |
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*/ |
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extern void i2c_init(void); |
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/**
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@brief Terminates the data transfer and releases the I2C bus
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@param void |
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@return none |
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*/ |
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extern void i2c_stop(void); |
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/**
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@brief Issues a start condition and sends address and transfer direction
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@param addr address and transfer direction of I2C device |
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@retval 0 device accessible
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@retval 1 failed to access device
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*/ |
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extern unsigned char i2c_start(unsigned char addr); |
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/**
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@brief Issues a repeated start condition and sends address and transfer direction
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@param addr address and transfer direction of I2C device |
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@retval 0 device accessible |
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@retval 1 failed to access device |
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*/ |
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extern unsigned char i2c_rep_start(unsigned char addr); |
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/**
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@brief Issues a start condition and sends address and transfer direction
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If device is busy, use ack polling to wait until device ready
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@param addr address and transfer direction of I2C device |
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@return none |
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*/ |
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extern void i2c_start_wait(unsigned char addr); |
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/**
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@brief Send one byte to I2C device |
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@param data byte to be transfered |
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@retval 0 write successful |
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@retval 1 write failed |
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*/ |
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extern unsigned char i2c_write(unsigned char data); |
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/**
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@brief read one byte from the I2C device, request more data from device
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@return byte read from I2C device |
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*/ |
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extern unsigned char i2c_readAck(void); |
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/**
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@brief read one byte from the I2C device, read is followed by a stop condition
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@return byte read from I2C device |
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*/ |
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extern unsigned char i2c_readNak(void); |
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/**
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@brief read one byte from the I2C device |
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Implemented as a macro, which calls either i2c_readAck or i2c_readNak |
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@param ack 1 send ack, request more data from device<br> |
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0 send nak, read is followed by a stop condition
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@return byte read from I2C device |
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*/ |
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extern unsigned char i2c_read(unsigned char ack); |
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#define i2c_read(ack) (ack) ? i2c_readAck() : i2c_readNak(); |
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/**@}*/ |
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#endif |
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@ -1,207 +0,0 @@ |
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/*************************************************************************
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* Title: I2C master library using hardware TWI interface |
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* Author: Peter Fleury <pfleury@gmx.ch> http://jump.to/fleury
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* File: $Id: twimaster.c,v 1.3 2005/07/02 11:14:21 Peter Exp $ |
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* Software: AVR-GCC 3.4.3 / avr-libc 1.2.3 |
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* Target: any AVR device with hardware TWI |
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* Usage: API compatible with I2C Software Library i2cmaster.h |
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**************************************************************************/ |
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#include <inttypes.h> |
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#include <compat/twi.h> |
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#include <i2cmaster.h> |
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/* define CPU frequency in Hz here if not defined in Makefile */ |
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#ifndef F_CPU |
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#define F_CPU 16000000UL |
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#endif |
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/* I2C clock in Hz */ |
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#define SCL_CLOCK 400000L |
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/*************************************************************************
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Initialization of the I2C bus interface. Need to be called only once |
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*************************************************************************/ |
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void i2c_init(void) |
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{ |
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/* initialize TWI clock
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* minimal values in Bit Rate Register (TWBR) and minimal Prescaler |
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* bits in the TWI Status Register should give us maximal possible |
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* I2C bus speed - about 444 kHz |
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* |
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* for more details, see 20.5.2 in ATmega16/32 secification |
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*/ |
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TWSR = 0; /* no prescaler */ |
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TWBR = 10; /* must be >= 10 for stable operation */ |
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}/* i2c_init */ |
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/*************************************************************************
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Issues a start condition and sends address and transfer direction. |
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return 0 = device accessible, 1= failed to access device |
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*************************************************************************/ |
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unsigned char i2c_start(unsigned char address) |
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{ |
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uint8_t twst; |
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/* send START condition */ |
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TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN); |
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/* wait until transmission completed */ |
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while(!(TWCR & (1<<TWINT))); |
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/* check value of TWI Status Register. Mask prescaler bits. */ |
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twst = TW_STATUS & 0xF8; |
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if ( (twst != TW_START) && (twst != TW_REP_START)) return 1; |
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/* send device address */ |
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TWDR = address; |
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TWCR = (1<<TWINT) | (1<<TWEN); |
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/* wail until transmission completed and ACK/NACK has been received */ |
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while(!(TWCR & (1<<TWINT))); |
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/* check value of TWI Status Register. Mask prescaler bits. */ |
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twst = TW_STATUS & 0xF8; |
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if ( (twst != TW_MT_SLA_ACK) && (twst != TW_MR_SLA_ACK) ) return 1; |
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return 0; |
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}/* i2c_start */ |
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/*************************************************************************
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Issues a start condition and sends address and transfer direction. |
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If device is busy, use ack polling to wait until device is ready |
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Input: address and transfer direction of I2C device |
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*************************************************************************/ |
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void i2c_start_wait(unsigned char address) |
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{ |
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uint8_t twst; |
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while ( 1 ) |
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{ |
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/* send START condition */ |
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TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN); |
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/* wait until transmission completed */ |
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while(!(TWCR & (1<<TWINT))); |
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/* check value of TWI Status Register. Mask prescaler bits. */ |
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twst = TW_STATUS & 0xF8; |
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if ( (twst != TW_START) && (twst != TW_REP_START)) continue; |
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/* send device address */ |
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TWDR = address; |
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TWCR = (1<<TWINT) | (1<<TWEN); |
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/* wail until transmission completed */ |
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while(!(TWCR & (1<<TWINT))); |
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/* check value of TWI Status Register. Mask prescaler bits. */ |
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twst = TW_STATUS & 0xF8; |
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if ( (twst == TW_MT_SLA_NACK )||(twst ==TW_MR_DATA_NACK) ) |
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{ |
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/* device busy, send stop condition to terminate write operation */ |
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TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO); |
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/* wait until stop condition is executed and bus released */ |
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while(TWCR & (1<<TWSTO)); |
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continue; |
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} |
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break; |
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} |
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}/* i2c_start_wait */ |
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/*************************************************************************
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Issues a repeated start condition and sends address and transfer direction |
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Input: address and transfer direction of I2C device |
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Return: 0 device accessible |
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1 failed to access device |
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*************************************************************************/ |
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unsigned char i2c_rep_start(unsigned char address) |
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{ |
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return i2c_start( address ); |
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}/* i2c_rep_start */ |
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/*************************************************************************
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Terminates the data transfer and releases the I2C bus |
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*************************************************************************/ |
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void i2c_stop(void) |
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{ |
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/* send stop condition */ |
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TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO); |
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/* wait until stop condition is executed and bus released */ |
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while(TWCR & (1<<TWSTO)); |
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}/* i2c_stop */ |
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/*************************************************************************
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Send one byte to I2C device |
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Input: byte to be transfered |
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Return: 0 write successful |
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1 write failed |
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*************************************************************************/ |
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unsigned char i2c_write( unsigned char data ) |
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{ |
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uint8_t twst; |
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/* send data to the previously addressed device */ |
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TWDR = data; |
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TWCR = (1<<TWINT) | (1<<TWEN); |
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/* wait until transmission completed */ |
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while(!(TWCR & (1<<TWINT))); |
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/* check value of TWI Status Register. Mask prescaler bits */ |
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twst = TW_STATUS & 0xF8; |
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if( twst != TW_MT_DATA_ACK) return 1; |
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return 0; |
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}/* i2c_write */ |
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/*************************************************************************
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Read one byte from the I2C device, request more data from device |
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Return: byte read from I2C device |
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*************************************************************************/ |
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unsigned char i2c_readAck(void) |
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{ |
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TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA); |
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while(!(TWCR & (1<<TWINT))); |
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return TWDR; |
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}/* i2c_readAck */ |
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/*************************************************************************
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Read one byte from the I2C device, read is followed by a stop condition |
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Return: byte read from I2C device |
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*************************************************************************/ |
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unsigned char i2c_readNak(void) |
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{ |
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TWCR = (1<<TWINT) | (1<<TWEN); |
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while(!(TWCR & (1<<TWINT))); |
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return TWDR; |
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}/* i2c_readNak */ |
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