/*
* Waiting for ACKNOWLEDGE.
*
* When a chip is being addressed or has received data it will issue an
* ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
* (set it to high level) and then release the CLOCK line.
* Now it must wait for the SLAVE to pull the DATA line low.
* Actually on the bus this looks like a START condition so nothing happens
* because of the fact that the IC's that have not been addressed are doing
* nothing.
*
* When the SLAVE has pulled this line low the MASTER will take the CLOCK
* line low and then the SLAVE will release the SDA (data) line.
*/
static int
iicbb_ack(device_t dev, int timeout)
{
int noack;
int k = 0;
I2C_SET(dev,0,1);
I2C_SET(dev,1,1);
do {
noack = I2C_GETSDA(dev);
if (!noack)
break;
DELAY(10);
k += 10;
} while (k < timeout);
I2C_SET(dev,0,1);
I2C_DEBUG(printf("%c ",noack?'-':'+'));
return (noack);
}
static u_char
iicbb_readbyte(device_t dev, int last, int timeout)
{
int i;
unsigned char data=0;
I2C_SET(dev,0,1);
for (i=7; i>=0; i--)
{
I2C_SET(dev,1,1);
if (I2C_GETSDA(dev))
data |= (1<<i);
I2C_SET(dev,0,1);
}
if (last) {
iicbb_one(dev, timeout);
} else {
iicbb_zero(dev, timeout);
}
I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+'));
return data;
}
/*
* Waiting for ACKNOWLEDGE.
*
* When a chip is being addressed or has received data it will issue an
* ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
* (set it to high level) and then release the CLOCK line.
* Now it must wait for the SLAVE to pull the DATA line low.
* Actually on the bus this looks like a START condition so nothing happens
* because of the fact that the IC's that have not been addressed are doing
* nothing.
*
* When the SLAVE has pulled this line low the MASTER will take the CLOCK
* line low and then the SLAVE will release the SDA (data) line.
*/
static int
iicbb_ack(device_t dev, int timeout)
{
struct iicbb_softc *sc = device_get_softc(dev);
int noack;
int k = 0;
I2C_SET(sc,dev,0,1);
I2C_SET(sc,dev,1,1);
do {
noack = I2C_GETSDA(dev);
if (!noack)
break;
DELAY(1);
k++;
} while (k < timeout);
I2C_SET(sc,dev,0,1);
I2C_DEBUG(printf("%c ",noack?'-':'+'));
return (noack);
}
