void __attribute__ ((noinline)) i2c_start(void)
{
if ( i2c_started != 0 )
{
/* if already started: do restart */
i2c_read_sda(); /* SDA = 1 */
i2c_delay();
i2c_read_scl();
/* clock stretching is not done */
/* while (i2c_read_scl() == 0) ; */
i2c_delay(); /* another delay, just to be sure... */
}
i2c_read_sda();
/*
if (i2c_read_sda() == 0)
{
// do something because arbitration is lost
}
*/
/* send the start condition, both lines go from 1 to 0 */
i2c_clear_sda();
i2c_delay();
i2c_clear_scl();
i2c_started = 1;
}
static uint8_t i2c_read_bit(void)
{
uint8_t val;
/* do not drive SDA */
i2c_read_sda();
i2c_delay();
i2c_read_scl_and_delay();
val = i2c_read_sda();
i2c_delay();
i2c_clear_scl();
return val;
}
uint8_t i2c_read_bit(void)
{
uint8_t val;
/* do not drive SDA */
i2c_read_sda();
i2c_delay();
i2c_read_scl();
/* clock stretching is not done */
/* while (i2c_read_scl() == 0) ; */
i2c_delay(); /* may not be required... */
val = i2c_read_sda();
i2c_delay();
i2c_clear_scl();
return val;
}
/* i2c_read_byte
Read a byte from I2C bus
=> ack = acknowlege bit to send after read
<= returns data read from the bus
*/
unsigned char i2c_read_byte(unsigned char ack)
{
unsigned char loop, byte;
i2c_set_sda();
/* read data msb first */
for(loop = 0; loop < 8; loop++)
{
byte = byte << 1;
i2c_set_scl();
i2c_delay();
if(i2c_read_sda()) byte = byte | 1;
i2c_clear_scl();
}
/* send ack bit */
if(ack)
i2c_set_sda();
else
i2c_clear_sda();
i2c_set_scl();
i2c_delay();
i2c_clear_scl();
i2c_set_sda();
return byte;
}
/* i2c_write_byte
Write a byte to I2C bus
=> byte = data to write out
<= return 0 if acknowleged by the slave
*/
unsigned char i2c_write_byte(unsigned char byte)
{
unsigned char loop, ack, original_byte = byte;
/* send data, msb first */
for(loop = 0; loop < 8; loop++)
{
if(byte & 0x80)
i2c_set_sda();
else
i2c_clear_sda();
i2c_set_scl();
i2c_delay();
i2c_clear_scl();
byte = byte << 1;
}
/* read ack bit from slave */
i2c_set_sda();
i2c_set_scl();
i2c_delay();
ack = i2c_read_sda();
i2c_clear_scl();
return ack;
}
static void i2c_write_bit(uint8_t val)
{
if (val)
i2c_read_sda();
else
i2c_clear_sda();
i2c_delay();
i2c_read_scl_and_delay();
i2c_clear_scl();
}
static void i2c_start(void)
{
if ( i2c_started != 0 )
{
/* if already started: do restart */
i2c_read_sda(); /* SDA = 1 */
i2c_delay();
i2c_read_scl_and_delay();
}
i2c_read_sda();
/*
if (i2c_read_sda() == 0)
{
// do something because arbitration is lost
}
*/
/* send the start condition, both lines go from 1 to 0 */
i2c_clear_sda();
i2c_delay();
i2c_clear_scl();
i2c_started = 1;
}
static void i2c_stop(void)
{
/* set SDA to 0 */
i2c_clear_sda();
i2c_delay();
/* now release all lines */
i2c_read_scl_and_delay();
/* set SDA to 1 */
i2c_read_sda();
i2c_delay();
i2c_started = 0;
}
void i2c_write_bit(uint8_t val)
{
if (val)
i2c_read_sda();
else
i2c_clear_sda();
i2c_delay();
i2c_read_scl();
/* clock stretching is not done */
/* while (i2c_read_scl() == 0) ; */
/* validation is skipped, because this will be the only master */
/* If SDA is high, check that nobody else is driving SDA */
/*
if (val && i2c_read_sda() == 0)
{
arbitration_lost();
}
*/
i2c_delay();
i2c_clear_scl();
}
void __attribute__ ((noinline)) i2c_stop(void)
{
/* set SDA to 0 */
i2c_clear_sda();
i2c_delay();
/* now release all lines */
i2c_read_scl();
/* clock stretching is not done */
/* while (i2c_read_scl() == 0) ; */
i2c_delay(); /* another delay, just to be sure... */
/* set SDA to 1 */
i2c_read_sda();
/*
if (i2c_read_sda() == 0)
{
// do something because arbitration is lost
}
*/
i2c_delay();
i2c_started = 0;
}
