//------------------------------------------------------------------------------
// Writes a byte to I2C and checks acknowledge
// returns 0 on success
//------------------------------------------------------------------------------
i2cError_t i2cSoftWriteByte(uint8_t txByte)
{
uint8_t mask;
i2cError_t err=0;
for (mask = 0x80; mask > 0; mask >>= 1) //shift bit for masking (8 times)
{
if ((mask & txByte) == 0) {
I2C_SDA_LO(); //write a bit to SDA-Line
}
else {
I2C_SDA_HI();
}
udelay(1);
I2C_SCL_HI();
udelay(5);
I2C_SCL_LO();
udelay(1);
}
I2C_SDA_IN(); //release SDA-line
I2C_SCL_HI(); //clk #9 for ack
udelay(5);
if (I2C_SDA_GET() != 0) {
err = I2C_ACK_ERROR; //check ack from i2c slave
}
I2C_SCL_LO();
udelay(5);
//udelay(20); //delay to see the package on scope
I2C_SDA_OUT();
return err; //return error code
}
//------------------------------------------------------------------------------
// Reads a byte from I2C
// Returns the byte received
// note: timing (delay) may have to be changed for different microcontroller
//------------------------------------------------------------------------------
uint8_t i2cSoftReadByte(i2cAck_t ack)
{
uint8_t mask, rxByte=0;
I2C_SDA_IN(); //release SDA-line
for (mask = 0x80; mask > 0; mask >>= 1) //shift bit for masking
{
I2C_SCL_HI(); //start clock on SCL-line
udelay(4);
if (I2C_SDA_GET() != 0) {
rxByte = (rxByte | mask); //read bit
}
I2C_SCL_LO();
udelay(1); //data hold time
}
if (ack) {
I2C_SDA_LO(); //send acknowledge if necessary
} else {
I2C_SDA_HI();
}
udelay(1);
I2C_SCL_HI(); //clk #9 for ack
udelay(5);
I2C_SCL_LO();
I2C_SDA_IN(); //release SDA-line
udelay(5);
//udelay(20); //delay to see the package on scope
return rxByte; //return received byte
}
/*
* Toggles in a single byte in master mode.
*
* Entry: SCL low, SDA any
* Exit: SCL low, SDA low with ack set, high else
*
* Change SDA only when SCL is low!
* Sample SDA short before setting SCL low!
*/
static uint8_t TwGet(GPIO_TWICB* icb, uint8_t ack)
{
uint8_t rc = 0;
int i;
/* SDA is input. */
I2C_SDA_HI();
NutMicroDelay (1 * icb->delay_unit);
for (i = 0x80; i; i >>= 1) {
NutMicroDelay (2 * icb->delay_unit);
I2C_SCL_HI();
NutMicroDelay (2 * icb->delay_unit);
while(I2C_SCL_GET() == 0)
{
/* Clock stretching*/
NutMicroDelay (2 * icb->delay_unit);
}
if (I2C_SDA_GET()) {
rc |= i;
}
I2C_SCL_LO();
}
if (ack)
{
/* Master sets acknowledge */
I2C_SDA_LO();
}
NutMicroDelay (2 * icb->delay_unit);
I2C_SCL_HI();
NutMicroDelay (2 * icb->delay_unit);
I2C_SCL_LO();
NutMicroDelay (2 * icb->delay_unit);
return rc;
}
//------------------------------------------------------------------------------
//Initializes the ports for I2C
//------------------------------------------------------------------------------
void i2cSoftInit(void)
{
I2C_SDA_OUT();
I2C_SCL_OUT();
I2C_SDA_LO();
I2C_SCL_LO();
I2C_SDA_HI();
I2C_SCL_HI();
}
/*
* Rising edge on the data line while the clock line is high indicates
* a stop condition.
*
* Entry: SCL low, SDA any
* Exit: SCL high, SDA high
*/
static void TwStop(GPIO_TWICB* icb)
{
I2C_SDA_LO();
NutMicroDelay (icb->delay_unit);
I2C_SCL_HI();
NutMicroDelay (2 * icb->delay_unit);
I2C_SDA_HI();
NutMicroDelay (8 * icb->delay_unit);
}
/*
* Toggles out a single byte in master mode.
*
* Entry: SCL low, SDA any
* Exit: SCL low, SDA high
*
* Change SDA only when SCL is low!
* Sample SDA short before setting SCL low!
*/
static int TwPut(GPIO_TWICB* icb, uint8_t octet)
{
int i;
for (i = 0x80; i; i >>= 1) {
/* Set the data bit. */
if (octet & i) {
I2C_SDA_HI();
} else {
I2C_SDA_LO();
}
/* Wait for data to stabilize. */
NutMicroDelay (2 * icb->delay_unit);
/* Toggle the clock. */
I2C_SCL_HI();
NutMicroDelay (2 * icb->delay_unit);
while(I2C_SCL_GET() == 0)
{
/* Clock stretching*/
NutMicroDelay (2 * icb->delay_unit);
}
I2C_SCL_LO();
}
/* Release data line to receive the ACK bit. */
I2C_SDA_HI();
NutMicroDelay (2 * icb->delay_unit);
I2C_SCL_HI();
NutMicroDelay (2 * icb->delay_unit);
if (I2C_SDA_GET()) {
i = -1;
} else {
i = 0;
}
I2C_SCL_LO();
NutMicroDelay (2 * icb->delay_unit);
return i;
}
