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#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/delay.h>
#include <stdlib.h>
#include "i2c.h"
I2C i2c;
void I2C::enable()
{
/*
* Set I2C clock frequency to 100kHz.
* freq = F_CPU / (16 + (2 * TWBR * TWPS) )
* let TWPS = "00" = 1
* -> TWBR = (F_CPU / 100000) - 16 / 2
*/
TWSR = 0; // the lower two bits control TWPS
TWBR = ((F_CPU / 100000UL) - 16) / 2;
}
// TODO Everything[tm] (error handling and generic code)
// Also TODO: Use interrupts instead of polling
void I2C::xmit(int num_tx, int num_rx, uint8_t *txbuf, uint8_t *rxbuf)
{
int i;
if (num_tx) {
TWCR = _BV(TWINT) | _BV(TWSTA) | _BV(TWEN);
while (!(TWCR & _BV(TWINT)));
TWDR = (I2C_EEPROM_ADDR << 1) | 0;
TWCR = _BV(TWINT) | _BV(TWEN);
while (!(TWCR & _BV(TWINT)));
for (i = 0; i < num_tx; i++) {
TWDR = txbuf[i];
TWCR = _BV(TWINT) | _BV(TWEN);
while (!(TWCR & _BV(TWINT)));
}
}
if (num_rx) {
TWCR = _BV(TWINT) | _BV(TWSTA) | _BV(TWEN);
while (!(TWCR & _BV(TWINT)));
TWDR = (I2C_EEPROM_ADDR << 1) | 1;
TWCR = _BV(TWINT) | _BV(TWEN);
while (!(TWCR & _BV(TWINT)));
for (i = 0; i < num_rx; i++) {
if (i == num_rx-1) {
TWCR = _BV(TWINT) | _BV(TWEN);
} else {
TWCR = _BV(TWINT) | _BV(TWEN) | _BV(TWEA);
}
while (!(TWCR & _BV(TWINT)));
rxbuf[i] = TWDR;
}
}
TWCR = _BV(TWINT) | _BV(TWSTO) | _BV(TWEN);
}
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