drashna/qmk_firmware
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i2c fix

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This commit is contained in:
Jack Humbert 2018-05-15 22:30:58 -04:00
parent 6dc215cd67
commit 682555faac
6 changed files with 33 additions and 29 deletions
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42
drivers/avr/i2c_master.c
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@ -13,32 +13,34 @@
void i2c_init(void)
{
TWSR = 0; /* no prescaler */
TWBR = (uint8_t)TWBR_val;
//TWBR = 10;
}
uint8_t i2c_start(uint8_t address)
{
// reset TWI control register
TWCR = 0;
// transmit START condition
//TWCR = 0;
// transmit START condition
TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);
// wait for end of transmission
while( !(TWCR & (1<<TWINT)) );
// check if the start condition was successfully transmitted
if((TWSR & 0xF8) != TW_START){ return 1; }
if(((TW_STATUS & 0xF8) != TW_START) && ((TW_STATUS & 0xF8) != TW_REP_START)){ return 1; }
// load slave address into data register
TWDR = address;
// start transmission of address
TWCR = (1<<TWINT) | (1<<TWEN);
// wait for end of transmission
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;
}
@ -50,17 +52,17 @@ uint8_t i2c_write(uint8_t data)
TWCR = (1<<TWINT) | (1<<TWEN);
// wait for end of transmission
while( !(TWCR & (1<<TWINT)) );
if( (TWSR & 0xF8) != TW_MT_DATA_ACK ){ return 1; }
if( (TW_STATUS & 0xF8) != TW_MT_DATA_ACK ){ return 1; }
return 0;
}
uint8_t i2c_read_ack(void)
{
// start TWI module and acknowledge data after reception
TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA);
TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA);
// wait for end of transmission
while( !(TWCR & (1<<TWINT)) );
// return received data from TWDR
@ -69,7 +71,7 @@ uint8_t i2c_read_ack(void)
uint8_t i2c_read_nack(void)
{
// start receiving without acknowledging reception
TWCR = (1<<TWINT) | (1<<TWEN);
// wait for end of transmission
@ -81,29 +83,29 @@ uint8_t i2c_read_nack(void)
uint8_t i2c_transmit(uint8_t address, uint8_t* data, uint16_t length)
{
if (i2c_start(address | I2C_WRITE)) return 1;
for (uint16_t i = 0; i < length; i++)
{
if (i2c_write(data[i])) return 1;
}
i2c_stop();
return 0;
}
uint8_t i2c_receive(uint8_t address, uint8_t* data, uint16_t length)
{
if (i2c_start(address | I2C_READ)) return 1;
for (uint16_t i = 0; i < (length-1); i++)
{
data[i] = i2c_read_ack();
}
data[(length-1)] = i2c_read_nack();
i2c_stop();
return 0;
}
@ -146,4 +148,6 @@ void i2c_stop(void)
{
// transmit STOP condition
TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
// wait until stop condition is executed and bus released
while(TWCR & (1<<TWSTO));
}