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Allow repeat start

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This commit is contained in:
Jeremy Soller 2020-10-20 20:54:26 -06:00
parent 095533fcd3
commit ce87dce512
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GPG Key ID: E988B49EE78A7FB1
1 changed files with 6 additions and 4 deletions
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10
keyboards/system76/launch_beta_1/i2c.c
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@ -12,9 +12,8 @@ void i2c_init(unsigned long baud) {
int i2c_start(uint8_t addr, bool read) {
uint32_t count;
uint8_t twst;
// reset TWI control register
TWCR = 0;
// transmit START condition
TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);
// wait for end of transmission
@ -23,7 +22,8 @@ int i2c_start(uint8_t addr, bool read) {
if (count == 0) return -1;
// check if the start condition was successfully transmitted
if((TWSR & 0xF8) != TW_START) return -1;
twst = TW_STATUS & 0xF8;
if ((twst != TW_START) && (twst != TW_REP_START)) return -1;
// load slave addr into data register
TWDR = ((addr << 1) | read);
@ -35,7 +35,7 @@ int i2c_start(uint8_t addr, bool read) {
if (count == 0) return -1;
// check if the device has acknowledged the READ / WRITE mode
uint8_t twst = TW_STATUS & 0xF8;
twst = TW_STATUS & 0xF8;
if ((twst != TW_MT_SLA_ACK) && (twst != TW_MR_SLA_ACK)) return -1;
return 0;
@ -44,6 +44,8 @@ int i2c_start(uint8_t addr, bool read) {
void i2c_stop(void) {
// transmit STOP condition
TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
//TODO: timeout?
while (TWCR & (1<<TWSTO));
}
int i2c_write(uint8_t * data, int length) {