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valeh
236
basic-setup/components/u8g2/sys/avr/avr-libc/lib/avr-hw-i2c/twimastertimeout.c
Executable file
236
basic-setup/components/u8g2/sys/avr/avr-libc/lib/avr-hw-i2c/twimastertimeout.c
Executable file
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/*
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* modified version of I2C master library
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* added a timeout variable for non blocking i2c
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*/
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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 <avr-hw-i2c/i2cmaster.h>
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#include <inttypes.h>
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#include <compat/twi.h>
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/* define CPU frequency in Mhz here if not defined in Makefile */
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#ifndef F_CPU
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#define F_CPU 4000000UL
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#endif
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/* I2C clock in Hz */
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#define SCL_CLOCK 100000L
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/* I2C timer max delay */
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#define I2C_TIMER_DELAY 0xFF
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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: 100 kHz clock, TWPS = 0 => prescaler = 1 */
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TWSR = 0; /* no prescaler */
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TWBR = ((F_CPU/SCL_CLOCK)-16)/2; /* 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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uint32_t i2c_timer = 0;
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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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i2c_timer = I2C_TIMER_DELAY;
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while(!(TWCR & (1<<TWINT)) && i2c_timer--);
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if(i2c_timer == 0)
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return 1;
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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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i2c_timer = I2C_TIMER_DELAY;
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while(!(TWCR & (1<<TWINT)) && i2c_timer--);
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if(i2c_timer == 0)
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return 1;
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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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uint32_t i2c_timer = 0;
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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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i2c_timer = I2C_TIMER_DELAY;
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while(!(TWCR & (1<<TWINT)) && i2c_timer--);
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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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i2c_timer = I2C_TIMER_DELAY;
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while(!(TWCR & (1<<TWINT)) && i2c_timer--);
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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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i2c_timer = I2C_TIMER_DELAY;
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while((TWCR & (1<<TWSTO)) && i2c_timer--);
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continue;
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}
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//if( twst != TW_MT_SLA_ACK) return 1;
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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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uint32_t i2c_timer = 0;
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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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i2c_timer = I2C_TIMER_DELAY;
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while((TWCR & (1<<TWSTO)) && i2c_timer--);
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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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uint32_t i2c_timer = 0;
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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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i2c_timer = I2C_TIMER_DELAY;
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while(!(TWCR & (1<<TWINT)) && i2c_timer--);
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if(i2c_timer == 0)
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return 1;
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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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uint32_t i2c_timer = 0;
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TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA);
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i2c_timer = I2C_TIMER_DELAY;
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while(!(TWCR & (1<<TWINT)) && i2c_timer--);
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if(i2c_timer == 0)
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return 0;
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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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uint32_t i2c_timer = 0;
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TWCR = (1<<TWINT) | (1<<TWEN);
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i2c_timer = I2C_TIMER_DELAY;
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while(!(TWCR & (1<<TWINT)) && i2c_timer--);
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if(i2c_timer == 0)
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return 0;
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return TWDR;
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}/* i2c_readNak */
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