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adds timeout to avr i2c

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This commit is contained in:
Jack Humbert 2018-06-12 23:37:06 -04:00
parent b8564f5dd0
commit bad56a4f2b
8 changed files with 163 additions and 80 deletions
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89
drivers/avr/i2c_master.c
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@ -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;
}