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/* Copyright (C) 2019 Elia Ritterbusch
+
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
/* 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"
#include "wait.h"
#ifndef F_SCL
# define F_SCL 400000UL // SCL frequency
#endif
#define TWBR_val (((F_CPU / F_SCL) - 16) / 2)
void i2c_init(void) {
TWSR = 0; /* no prescaler */
TWBR = (uint8_t)TWBR_val;
#ifdef __AVR_ATmega32A__
// set pull-up resistors on I2C bus pins
PORTC |= 0b11;
// enable TWI (two-wire interface)
TWCR |= (1 << TWEN);
// enable TWI interrupt and slave address ACK
TWCR |= (1 << TWIE);
TWCR |= (1 << TWEA);
#endif
}
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, const uint8_t* data, uint16_t length, uint16_t timeout) {
i2c_status_t status = i2c_start(address | I2C_WRITE, timeout);
for (uint16_t i = 0; i < length && status >= 0; i++) {
status = i2c_write(data[i], timeout);
}
i2c_stop();
return status;
}
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);
for (uint16_t i = 0; i < (length - 1) && status >= 0; i++) {
status = i2c_read_ack(timeout);
if (status >= 0) {
data[i] = status;
}
}
if (status >= 0) {
status = i2c_read_nack(timeout);
if (status >= 0) {
data[(length - 1)] = status;
}
}
i2c_stop();
return (status < 0) ? status : I2C_STATUS_SUCCESS;
}
i2c_status_t i2c_writeReg(uint8_t devaddr, uint8_t regaddr, const uint8_t* data, uint16_t length, uint16_t timeout) {
i2c_status_t status = i2c_start(devaddr | 0x00, timeout);
if (status >= 0) {
status = i2c_write(regaddr, timeout);
for (uint16_t i = 0; i < length && status >= 0; i++) {
status = i2c_write(data[i], timeout);
}
}
i2c_stop();
return status;
}
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 < 0) {
goto error;
}
status = i2c_write(regaddr, timeout);
if (status < 0) {
goto error;
}
status = i2c_start(devaddr | 0x01, timeout);
for (uint16_t i = 0; i < (length - 1) && status >= 0; i++) {
status = i2c_read_ack(timeout);
if (status >= 0) {
data[i] = status;
}
}
if (status >= 0) {
status = i2c_read_nack(timeout);
if (status >= 0) {
data[(length - 1)] = status;
}
}
error:
i2c_stop();
return (status < 0) ? status : I2C_STATUS_SUCCESS;
}
void i2c_stop(void) {
// transmit STOP condition
TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO);
}
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