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i2c.c: add debugging aid. 

No functional change.
This commit is contained in:
Markus Hitter 2016-04-25 21:05:11 +02:00
parent a47c4b40df
commit dcc970d2fd
1 changed files with 38 additions and 1 deletions
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39
i2c.c
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@ -255,17 +255,33 @@ void i2c_write(uint8_t data, uint8_t last_byte) {
Bit 0 (TWIE) enables TWI interrupt.
*/
//#define TWI_INTERRUPT_DEBUG
#ifdef TWI_INTERRUPT_DEBUG
#include "serial.h"
#include "sendf.h"
#endif
ISR(TWI_vect) {
uint8_t status = TWSR & TW_STATUS_MASK;
switch (TWSR & TW_STATUS_MASK) {
#ifdef TWI_INTERRUPT_DEBUG
serial_writechar('.');
#endif
switch (status) {
case TW_BUS_ERROR:
// A hardware error was detected.
#ifdef TWI_INTERRUPT_DEBUG
serial_writechar('1');
#endif
i2c_state |= I2C_ERROR_BUS_FAIL;
// Send stop condition.
TWCR = (1<<TWINT)|(I2C_MODE<<TWEA)|(0<<TWSTA)|(1<<TWSTO)|(1<<TWEN)|(0<<TWIE);
break;
case TW_START:
// Start happens, send a target address.
#ifdef TWI_INTERRUPT_DEBUG
serial_writechar('2');
#endif
if ((i2c_state & I2C_MODE_MASK) == I2C_MODE_SARP) {
i2c_address |= 0x01;
} else {
@ -276,6 +292,9 @@ ISR(TWI_vect) {
break;
case TW_REP_START:
// Start happens, send a target address.
#ifdef TWI_INTERRUPT_DEBUG
serial_writechar('3');
#endif
if ((i2c_state & I2C_MODE_MASK) == I2C_MODE_ENHA) {
i2c_address |= 0x01;
} else {
@ -286,6 +305,9 @@ ISR(TWI_vect) {
break;
case TW_MT_SLA_ACK:
// SLA+W was sent, then ACK received.
#ifdef TWI_INTERRUPT_DEBUG
serial_writechar('4');
#endif
if ((i2c_state & I2C_MODE_MASK) == I2C_MODE_SAWP && buf_canread(send)) {
buf_pop(send, TWDR);
TWCR = (1<<TWINT)|(I2C_MODE<<TWEA)|(0<<TWSTA)|(0<<TWSTO)|(1<<TWEN)|(1<<TWIE);
@ -299,12 +321,18 @@ ISR(TWI_vect) {
break;
case TW_MT_SLA_NACK:
// SLA+W was sent, got NACK, so slave is busy or out of bus.
#ifdef TWI_INTERRUPT_DEBUG
serial_writechar('5');
#endif
i2c_state |= I2C_ERROR_NO_ANSWER;
// Send stop condition.
TWCR = (1<<TWINT)|(I2C_MODE<<TWEA)|(0<<TWSTA)|(1<<TWSTO)|(1<<TWEN)|(0<<TWIE);
break;
case TW_MT_DATA_ACK:
// A byte was sent, got ACK.
#ifdef TWI_INTERRUPT_DEBUG
serial_writechar('6');
#endif
if ((i2c_state & I2C_MODE_MASK) == I2C_MODE_SAWP) {
if (buf_canread(send)) {
// Send the next byte.
@ -336,12 +364,18 @@ ISR(TWI_vect) {
// Byte was sent but got NACK, there are two possible reasons:
// - a slave stops transmission and it is ok, or
// - a slave became crazy.
#ifdef TWI_INTERRUPT_DEBUG
serial_writechar('7');
#endif
i2c_state |= I2C_ERROR_NACK;
// Send stop condition.
TWCR = (1<<TWINT)|(I2C_MODE<<TWEA)|(0<<TWSTA)|(1<<TWSTO)|(1<<TWEN)|(0<<TWIE);
break;
case TW_MT_ARB_LOST: // Collision, identical to TW_MR_ARB_LOST.
// It looks like there is another master on the bus.
#ifdef TWI_INTERRUPT_DEBUG
serial_writechar('8');
#endif
i2c_state |= I2C_ERROR_LOW_PRIO;
// Setup all again.
sendtail = sendhead;
@ -485,6 +519,9 @@ ISR(TWI_vect) {
#endif /* I2C_SLAVE_MODE */
default:
#ifdef TWI_INTERRUPT_DEBUG
sendf_P(serial_writechar, PSTR("(%sx)"), status);
#endif
break;
}
}