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Add i2c capability for AVR

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This commit is contained in:
Jeremy Soller
2019-10-01 14:20:35 -06:00
parent f50b8feb83
commit 044584e96e
7 changed files with 245 additions and 0 deletions
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163
src/arch/avr/i2c.c Normal file
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#include <stdio.h>
#include <avr/io.h>
#include <util/twi.h>
#include <arch/i2c.h>
#include <board/cpu.h>
#define TIMEOUT (F_CPU/1000)
#define I2C_READ 0x01
#define I2C_WRITE 0x00
uint8_t i2c_start(uint8_t addr, uint8_t rw) {
uint32_t count;
// reset TWI control register
TWCR = 0;
// transmit START condition
TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);
// wait for end of transmission
count = TIMEOUT;
while(!(TWCR & (1<<TWINT)) && count > 0) count -= 1;
if (count == 0) {
printf("i2c_start timed out waiting to send start to 0x%X\n", addr);
return 1;
}
// check if the start condition was successfully transmitted
if((TWSR & 0xF8) != TW_START){
printf("i2c_start failed to send start condition to 0x%X\n", addr);
return 1;
}
// load slave addr into data register
TWDR = ((addr << 1) | rw);
// start transmission of addr
TWCR = (1<<TWINT) | (1<<TWEN);
// wait for end of transmission
count = TIMEOUT;
while(!(TWCR & (1<<TWINT)) && count > 0) count -= 1;
if (count == 0) {
printf("i2c_start timed out waiting to send addr to 0x%X\n", addr);
return 1;
}
// 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)) {
printf("i2c_start failed to receive ack from 0x%X\n", addr);
return 1;
}
return 0;
}
void i2c_stop() {
// transmit STOP condition
TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
}
uint8_t i2c_write(uint8_t data) {
uint32_t count;
// load data into data register
TWDR = data;
// start transmission of data
TWCR = (1<<TWINT) | (1<<TWEN);
// wait for end of transmission
count = TIMEOUT;
while(!(TWCR & (1<<TWINT)) && count > 0) count -= 1;
if (count == 0) {
printf("i2c_write timed out waiting to send 0x%X\n", data);
return 1;
}
if( (TWSR & 0xF8) != TW_MT_DATA_ACK ){
printf("i2c_write failed to receive ack for 0x%X\n", data);
return 1;
}
return 0;
}
uint8_t i2c_read_ack() {
// start TWI module and acknowledge data after reception
TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA);
// wait for end of transmission
while( !(TWCR & (1<<TWINT)) );
// return received data from TWDR
return TWDR;
}
uint8_t i2c_read_nack() {
// start receiving without acknowledging reception
TWCR = (1<<TWINT) | (1<<TWEN);
// wait for end of transmission
while( !(TWCR & (1<<TWINT)) );
// return received data from TWDR
return TWDR;
}
uint8_t i2c_recv(uint8_t addr, uint8_t* data, uint16_t length) {
if (i2c_start(addr, I2C_READ)) return 1;
uint16_t i;
for (i = 0; i < (length-1); i++)
{
data[i] = i2c_read_ack();
}
data[(length-1)] = i2c_read_nack();
i2c_stop();
return 0;
}
uint8_t i2c_send(uint8_t addr, uint8_t* data, uint16_t length) {
if (i2c_start(addr, I2C_WRITE)) return 1;
uint16_t i;
for (i = 0; i < length; i++) {
if (i2c_write(data[i])) return 1;
}
i2c_stop();
return 0;
}
uint8_t i2c_get(uint8_t addr, uint8_t reg, uint8_t* data, uint16_t length) {
if (i2c_start(addr, I2C_WRITE)) return 1;
if (i2c_write(reg)) return 1;
if (i2c_start(addr, I2C_READ)) return 1;
uint16_t i;
for (i = 0; i < (length-1); i++)
{
data[i] = i2c_read_ack();
}
data[(length-1)] = i2c_read_nack();
i2c_stop();
return 0;
}
uint8_t i2c_set(uint8_t addr, uint8_t reg, uint8_t* data, uint16_t length) {
if (i2c_start(addr, I2C_WRITE)) return 1;
if(i2c_write(reg)) return 1;
uint16_t i;
for (i = 0; i < length; i++)
{
if (i2c_write(data[i])) return 1;
}
i2c_stop();
return 0;
}