/*
* This function reads one byte from the slave device
*
* Parameters:
* ack - Flag to indicate either to send the acknowledge
* message to the slave device or not
*
* Return Value:
* One byte data read from the Slave device
*/
static unsigned char swI2CReadByte(unsigned char ack)
{
int i;
unsigned char data = 0;
for(i=7; i>=0; i--)
{
/* Set the SCL to Low and SDA to High (Input) */
swI2CSCL(0);
swI2CSDA(1);
swI2CWait();
/* Set the SCL High */
swI2CSCL(1);
swI2CWait();
/* Read data bits from SDA */
data |= (swI2CReadSDA() << i);
}
if (ack)
swI2CAck();
/* Set the SCL Low and SDA High */
swI2CSCL(0);
swI2CSDA(1);
return data;
}
/*******************************************************************************
swI2CWriteByte
This function writes one byte to the slave device
Parameters:
data - Data to be write to the slave device
Return Value:
0 - Fail to write byte
1 - Success
*******************************************************************************/
unsigned char swI2CWriteByte(unsigned char data)
{
unsigned char value = data;
int i;
/* Sending the data bit by bit */
for (i=0; i<8; i++)
{
/* Set SCL to low */
swI2CSCL(0);
/* Send data bit */
if ((value & 0x80) != 0)
swI2CSDA(1);
else
swI2CSDA(0);
swI2CWait();
/* Toggle clk line to one */
swI2CSCL(1);
/* Shift byte to be sent */
value = value << 1;
}
/* Set the SCL Low and SDA High (prepare to get input) */
swI2CSCL(0);
swI2CSDA(1);
/* Set the SCL High for ack */
swI2CWait();
swI2CSCL(1);
/* Read SDA, until SDA==0 */
for(i=0; i<0xff; i++)
{
swI2CWait();
swI2CWait();
if (!swI2CReadSDA())
break;
}
/* Set the SCL Low and SDA High */
swI2CSCL(0);
swI2CSDA(1);
return (i<0xff);
}
/*******************************************************************************
swI2CSDA
This function set/reset the SDA GPIO pin
Parameters:
value - Bit value to set to the SCL or SDA (0 = low, 1 = high)
Return Value:
None
*******************************************************************************/
static void swI2CSDA(unsigned char value)
{
uint32_t ulGPIOData;
uint32_t ulGPIODirection;
ulGPIODirection = peekRegisterDWord(g_i2cDataGPIODataDirReg);
if (value) /* High */
{
/* Set direction as input. This will automatically pull the signal up. */
ulGPIODirection &= ~(1 << g_i2cDataGPIO);
pokeRegisterDWord(g_i2cDataGPIODataDirReg, ulGPIODirection);
}
else /* Low */
{
/* Set the signal down */
ulGPIOData = peekRegisterDWord(g_i2cDataGPIODataReg);
ulGPIOData &= ~(1 << g_i2cDataGPIO);
pokeRegisterDWord(g_i2cDataGPIODataReg, ulGPIOData);
/* Set direction as output */
ulGPIODirection |= (1 << g_i2cDataGPIO);
pokeRegisterDWord(g_i2cDataGPIODataDirReg, ulGPIODirection);
}
swI2CWait();
}
/*******************************************************************************
swI2CReadSDA
This function read the data from the SDA GPIO pin
Parameters:
None
Return Value:
The SDA data bit sent by the Slave
*******************************************************************************/
static unsigned char swI2CReadSDA()
{
unsigned char data;
uint32_t ulGPIODirection;
uint32_t ulGPIOData;
/* Make sure that the direction is input (High) */
ulGPIODirection = peekRegisterDWord(g_i2cDataGPIODataDirReg);
if ((ulGPIODirection & (1 << g_i2cDataGPIO)) != (~(1 << g_i2cDataGPIO)))
{
ulGPIODirection &= ~(1 << g_i2cDataGPIO);
pokeRegisterDWord(g_i2cDataGPIODataDirReg, ulGPIODirection);
}
/* Now read the SDA line */
ulGPIOData = peekRegisterDWord(g_i2cDataGPIODataReg);
if (ulGPIOData & (1 << g_i2cDataGPIO))
return 1;
else
return 0;
swI2CWait();
}
