diff options
Diffstat (limited to 'drivers/avr/i2c_master.c')
| -rwxr-xr-x | drivers/avr/i2c_master.c | 89 |
1 files changed, 77 insertions, 12 deletions
diff --git a/drivers/avr/i2c_master.c b/drivers/avr/i2c_master.c index cd3c2e1c8..97f690043 100755 --- a/drivers/avr/i2c_master.c +++ b/drivers/avr/i2c_master.c @@ -6,6 +6,7 @@ #include <util/twi.h> #include "i2c_master.h" +#include "timer.h" #define F_SCL 400000UL // SCL frequency #define Prescaler 1 @@ -24,8 +25,18 @@ uint8_t i2c_start(uint8_t address) TWCR = 0; // transmit START condition TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN); - // wait for end of transmission - while( !(TWCR & (1<<TWINT)) ); + + #ifdef I2C_TIMEOUT + uint16_t timeout_timer = timer_read(); + while( !(TWCR & (1<<TWINT)) ) { + if ((timer_read() - timeout_timer) > I2C_TIMEOUT) { + return 2; // should make these codes standard + } + } + #else + // wait for end of transmission + while( !(TWCR & (1<<TWINT)) ); + #endif // check if the start condition was successfully transmitted if(((TW_STATUS & 0xF8) != TW_START) && ((TW_STATUS & 0xF8) != TW_REP_START)){ return 1; } @@ -34,8 +45,18 @@ uint8_t i2c_start(uint8_t address) TWDR = address; // start transmission of address TWCR = (1<<TWINT) | (1<<TWEN); - // wait for end of transmission - while( !(TWCR & (1<<TWINT)) ); + + #ifdef I2C_TIMEOUT + timeout_timer = timer_read(); + while( !(TWCR & (1<<TWINT)) ) { + if ((timer_read() - timeout_timer) > I2C_TIMEOUT) { + return 2; // should make these codes standard + } + } + #else + // wait for end of transmission + while( !(TWCR & (1<<TWINT)) ); + #endif // check if the device has acknowledged the READ / WRITE mode uint8_t twst = TW_STATUS & 0xF8; @@ -50,8 +71,18 @@ uint8_t i2c_write(uint8_t data) TWDR = data; // start transmission of data TWCR = (1<<TWINT) | (1<<TWEN); + + #ifdef I2C_TIMEOUT + uint16_t timeout_timer = timer_read(); + while( !(TWCR & (1<<TWINT)) ) { + if ((timer_read() - timeout_timer) > I2C_TIMEOUT) { + return 2; // should make these codes standard + } + } + #else // wait for end of transmission - while( !(TWCR & (1<<TWINT)) ); + while( !(TWCR & (1<<TWINT)) ); + #endif if( (TW_STATUS & 0xF8) != TW_MT_DATA_ACK ){ return 1; } @@ -63,8 +94,19 @@ uint8_t i2c_read_ack(void) // start TWI module and acknowledge data after reception TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA); - // wait for end of transmission - while( !(TWCR & (1<<TWINT)) ); + + #ifdef I2C_TIMEOUT + uint16_t timeout_timer = timer_read(); + while( !(TWCR & (1<<TWINT)) ) { + if ((timer_read() - timeout_timer) > I2C_TIMEOUT) { + return 2; // should make these codes standard + } + } + #else + // wait for end of transmission + while( !(TWCR & (1<<TWINT)) ); + #endif + // return received data from TWDR return TWDR; } @@ -74,8 +116,19 @@ uint8_t i2c_read_nack(void) // start receiving without acknowledging reception TWCR = (1<<TWINT) | (1<<TWEN); - // wait for end of transmission - while( !(TWCR & (1<<TWINT)) ); + + #ifdef I2C_TIMEOUT + uint16_t timeout_timer = timer_read(); + while( !(TWCR & (1<<TWINT)) ) { + if ((timer_read() - timeout_timer) > I2C_TIMEOUT) { + return 2; // should make these codes standard + } + } + #else + // wait for end of transmission + while( !(TWCR & (1<<TWINT)) ); + #endif + // return received data from TWDR return TWDR; } @@ -144,10 +197,22 @@ uint8_t i2c_readReg(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t le return 0; } -void i2c_stop(void) +uint8_t 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)); + + #ifdef I2C_TIMEOUT + uint16_t timeout_timer = timer_read(); + while(TWCR & (1<<TWSTO)) { + if ((timer_read() - timeout_timer) > I2C_TIMEOUT) { + return 2; // should make these codes standard + } + } + #else + // wait for end of transmission + while(TWCR & (1<<TWSTO)); + #endif + + return 0; } |