mirror of
https://github.com/qmk/qmk_firmware.git
synced 2024-11-30 06:55:51 +00:00
105 lines
2.4 KiB
C
105 lines
2.4 KiB
C
/*
|
|
Copyright 2016 Luiz Ribeiro <luizribeiro@gmail.com>
|
|
|
|
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 2 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 <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#include <avr/io.h>
|
|
#include <util/twi.h>
|
|
|
|
#include "i2c.h"
|
|
|
|
void i2c_set_bitrate(uint16_t bitrate_khz) {
|
|
uint8_t bitrate_div = ((F_CPU / 1000l) / bitrate_khz);
|
|
if (bitrate_div >= 16) {
|
|
bitrate_div = (bitrate_div - 16) / 2;
|
|
}
|
|
TWBR = bitrate_div;
|
|
}
|
|
|
|
void i2c_init(void) {
|
|
// set pull-up resistors on I2C bus pins
|
|
PORTC |= 0b11;
|
|
|
|
i2c_set_bitrate(400);
|
|
|
|
// enable TWI (two-wire interface)
|
|
TWCR |= (1 << TWEN);
|
|
|
|
// enable TWI interrupt and slave address ACK
|
|
TWCR |= (1 << TWIE);
|
|
TWCR |= (1 << TWEA);
|
|
}
|
|
|
|
uint8_t i2c_start(uint8_t address) {
|
|
// reset TWI control register
|
|
TWCR = 0;
|
|
|
|
// begin transmission and wait for it to end
|
|
TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);
|
|
while (!(TWCR & (1<<TWINT)));
|
|
|
|
// check if the start condition was successfully transmitted
|
|
if ((TWSR & 0xF8) != TW_START) {
|
|
return 1;
|
|
}
|
|
|
|
// transmit address and wait
|
|
TWDR = address;
|
|
TWCR = (1<<TWINT) | (1<<TWEN);
|
|
while (!(TWCR & (1<<TWINT)));
|
|
|
|
// 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 1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
void i2c_stop(void) {
|
|
TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
|
|
}
|
|
|
|
uint8_t i2c_write(uint8_t data) {
|
|
TWDR = data;
|
|
|
|
// transmit data and wait
|
|
TWCR = (1<<TWINT) | (1<<TWEN);
|
|
while (!(TWCR & (1<<TWINT)));
|
|
|
|
if ((TWSR & 0xF8) != TW_MT_DATA_ACK) {
|
|
return 1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
uint8_t i2c_send(uint8_t address, uint8_t *data, uint16_t length) {
|
|
if (i2c_start(address)) {
|
|
return 1;
|
|
}
|
|
|
|
for (uint16_t i = 0; i < length; i++) {
|
|
if (i2c_write(data[i])) {
|
|
return 1;
|
|
}
|
|
}
|
|
|
|
i2c_stop();
|
|
|
|
return 0;
|
|
}
|