178 lines
5.3 KiB
C
178 lines
5.3 KiB
C
#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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