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130 lines
2.6 KiB
130 lines
2.6 KiB
#include <stdint.h>
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#include <avr/io.h>
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#include <avr/pgmspace.h>
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#include <util/twi.h>
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#include <util/delay.h>
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#include "i2c_simple.h"
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#include "debug.h"
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//#define I2C_WAIT() while(!(TWCR & _BV(TWINT)))
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#define I2C_WAIT() i2c_wait();
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void inline i2c_wait(){
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uint16_t cntr=0;
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while(!(TWCR & _BV(TWINT))){
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cntr++;
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if(cntr >= 1000){
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printf("i2c waittime exceeded!\n");
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}
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}
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}
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void i2c_init()
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{
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TWBR = 32;//bit rate: 100kbit
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TWSR = 0;//Prescaler
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// TWAR = 0x80;//our address 1000 000, don't listen to general call
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// TWAMR = 0;
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TWCR = _BV(TWEA) | _BV(TWEN);/* _BV(TWINT) clear -> we must do something; unset _BV(TWSTA) manually!, _BV(TWSTO) */
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//TWDR - data
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}
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uint8_t i2c_read(uint8_t addr, uint8_t len, uint8_t *data)
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{
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TWCR |= _BV(TWINT) | _BV(TWSTA);
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I2C_WAIT();
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/* no error possible */
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TWDR = addr | 1;
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TWCR &= ~(_BV(TWSTA));
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TWCR |= _BV(TWINT);
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I2C_WAIT();
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/* possible results: ACK, NAK, abitration lost */
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if(TW_STATUS == TW_MR_SLA_NACK)
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{
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TWCR |= _BV(TWINT) | _BV(TWSTO);
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return 0;
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}
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else if(TW_STATUS == TW_MR_ARB_LOST) {return 0;}
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uint8_t done = 0;
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while(done + 1 < len)
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{
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TWCR |= _BV(TWEA) | _BV(TWINT);/* send ack after byte */
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I2C_WAIT();
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data[done] = TWDR;
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done++;
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TWCR |= _BV(TWINT);
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}
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TWCR &= ~_BV(TWEA);
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TWCR |= _BV(TWINT);/* send nak after byte */
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I2C_WAIT();
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data[done] = TWDR;
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done++;
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TWCR |= _BV(TWINT) | _BV(TWSTO);
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_delay_us(20); // wait about 2 bit periods
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return done;
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}
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uint8_t i2c_write_i(uint8_t addr, uint8_t len, uint8_t *data, uint8_t stop)
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{
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TWCR |= _BV(TWINT) | _BV(TWSTA);
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I2C_WAIT();
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/* no error possible */
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TWDR = addr;
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TWCR &= ~(_BV(TWSTA));
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TWCR |= _BV(TWINT);
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I2C_WAIT();
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/* possible results: ACK, NAK, abitration lost */
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if(TW_STATUS == TW_MT_SLA_NACK)
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{
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TWCR |= _BV(TWINT) | _BV(TWSTO);
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return 0;
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}
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else if(TW_STATUS == TW_MT_ARB_LOST) {return 0;}
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uint8_t done = 0;
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while(done < len)
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{
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TWDR = data[done];
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TWCR |= _BV(TWINT);
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I2C_WAIT();
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/* possible results: ACK, NAK, abitration lost */
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if(TW_STATUS == TW_MT_DATA_NACK)
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{
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TWCR |= _BV(TWINT) | _BV(TWSTO);
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return done;
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}
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else if(TW_STATUS == TW_MT_ARB_LOST) {return done;}
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done++;
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}
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if(stop) {TWCR |= _BV(TWINT) | _BV(TWSTO);}
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_delay_us(20); // wait about 2 bit periods
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return done;
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}
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inline uint8_t i2c_write(uint8_t addr, uint8_t len, uint8_t *data)
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{
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return i2c_write_i(addr, len, data, 1);
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}
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uint8_t i2c_write_read(uint8_t addr, uint8_t writelen, uint8_t *writedata, uint8_t readlen, uint8_t *readdata)
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{
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if(writelen == i2c_write_i(addr, writelen, writedata, 0)) {
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return i2c_read(addr, readlen, readdata);
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}
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return 0;
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}
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