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/* Library made by: g4lvanix
* Github repository: https://github.com/g4lvanix/I2C-master-lib
*/
#include <avr/io.h>
#include <util/twi.h>
#include "i2c_master.h"
#include "timer.h"
#define F_SCL 400000UL // SCL frequency
#define Prescaler 1
#define TWBR_val ((((F_CPU / F_SCL) / Prescaler) - 16 ) / 2)
void i2c_init(void)
{
TWSR = 0; /* no prescaler */
TWBR = (uint8_t)TWBR_val;
}
i2c_status_t i2c_start(uint8_t address, uint16_t timeout)
{
// reset TWI control register
TWCR = 0;
// transmit START condition
TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);
uint16_t timeout_timer = timer_read();
while( !(TWCR & (1<<TWINT)) ) {
if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) {
return I2C_STATUS_TIMEOUT;
}
}
// check if the start condition was successfully transmitted
if(((TW_STATUS & 0xF8) != TW_START) && ((TW_STATUS & 0xF8) != TW_REP_START)){ return I2C_STATUS_ERROR; }
// load slave address into data register
TWDR = address;
// start transmission of address
TWCR = (1<<TWINT) | (1<<TWEN);
timeout_timer = timer_read();
while( !(TWCR & (1<<TWINT)) ) {
if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) {
return I2C_STATUS_TIMEOUT;
}
}
// check if the device has acknowledged the READ / WRITE mode
uint8_t twst = TW_STATUS & 0xF8;
if ( (twst != TW_MT_SLA_ACK) && (twst != TW_MR_SLA_ACK) ) return I2C_STATUS_ERROR;
return I2C_STATUS_SUCCESS;
}
i2c_status_t i2c_write(uint8_t data, uint16_t timeout)
{
// load data into data register
TWDR = data;
// start transmission of data
TWCR = (1<<TWINT) | (1<<TWEN);
uint16_t timeout_timer = timer_read();
while( !(TWCR & (1<<TWINT)) ) {
if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) {
return I2C_STATUS_TIMEOUT;
}
}
if( (TW_STATUS & 0xF8) != TW_MT_DATA_ACK ){ return I2C_STATUS_ERROR; }
return I2C_STATUS_SUCCESS;
}
int16_t i2c_read_ack(uint16_t timeout)
{
// start TWI module and acknowledge data after reception
TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA);
uint16_t timeout_timer = timer_read();
while( !(TWCR & (1<<TWINT)) ) {
if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) {
return I2C_STATUS_TIMEOUT;
}
}
// return received data from TWDR
return TWDR;
}
int16_t i2c_read_nack(uint16_t timeout)
{
// start receiving without acknowledging reception
TWCR = (1<<TWINT) | (1<<TWEN);
uint16_t timeout_timer = timer_read();
while( !(TWCR & (1<<TWINT)) ) {
if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) {
return I2C_STATUS_TIMEOUT;
}
}
// return received data from TWDR
return TWDR;
}
i2c_status_t i2c_transmit(uint8_t address, uint8_t* data, uint16_t length, uint16_t timeout)
{
i2c_status_t status = i2c_start(address | I2C_WRITE, timeout);
if (status) return status;
for (uint16_t i = 0; i < length; i++) {
status = i2c_write(data[i], timeout);
if (status) return status;
}
status = i2c_stop(timeout);
if (status) return status;
return I2C_STATUS_SUCCESS;
}
i2c_status_t i2c_receive(uint8_t address, uint8_t* data, uint16_t length, uint16_t timeout)
{
i2c_status_t status = i2c_start(address | I2C_READ, timeout);
if (status) return status;
for (uint16_t i = 0; i < (length-1); i++) {
status = i2c_read_ack(timeout);
if (status >= 0) {
data[i] = status;
} else {
return status;
}
}
status = i2c_read_nack(timeout);
if (status >= 0 ) {
data[(length-1)] = status;
} else {
return status;
}
status = i2c_stop(timeout);
if (status) return status;
return I2C_STATUS_SUCCESS;
}
i2c_status_t i2c_writeReg(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout)
{
i2c_status_t status = i2c_start(devaddr | 0x00, timeout);
if (status) return status;
status = i2c_write(regaddr, timeout);
if (status) return status;
for (uint16_t i = 0; i < length; i++) {
status = i2c_write(data[i], timeout);
if (status) return status;
}
status = i2c_stop(timeout);
if (status) return status;
return I2C_STATUS_SUCCESS;
}
i2c_status_t i2c_readReg(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout)
{
i2c_status_t status = i2c_start(devaddr, timeout);
if (status) return status;
status = i2c_write(regaddr, timeout);
if (status) return status;
status = i2c_start(devaddr | 0x01, timeout);
if (status) return status;
for (uint16_t i = 0; i < (length-1); i++) {
status = i2c_read_ack(timeout);
if (status >= 0) {
data[i] = status;
} else {
return status;
}
}
status = i2c_read_nack(timeout);
if (status >= 0 ) {
data[(length-1)] = status;
} else {
return status;
}
status = i2c_stop(timeout);
if (status) return status;
return I2C_STATUS_SUCCESS;
}
i2c_status_t i2c_stop(uint16_t timeout)
{
// transmit STOP condition
TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
uint16_t timeout_timer = timer_read();
while(TWCR & (1<<TWSTO)) {
if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) {
return I2C_STATUS_TIMEOUT;
}
}
return I2C_STATUS_SUCCESS;
}
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