/*********************************************************************
* @fn hali2cStart
* @brief Initiates SM-Bus communication. Makes sure that both the
* clock and data lines of the SM-Bus are high. Then the data
* line is set high and clock line is set low to start I/O.
* @param void
* @return void
*/
STATIC void hali2cStart( void )
{
uint8 retry = HAL_I2C_RETRY_CNT;
// set SCL to input but with pull-up. if slave is pulling down it will stay down.
hali2cClock(1);
do {
// wait for slave to release clock line...
if (OCM_SCL) // wait until the line is high...
{
break;
}
hali2cWait(1);
} while ( --retry );
// SCL low to set SDA high so the transition will be correct.
hali2cClock(0);
OCM_DATA_HIGH(); // SDA high
hali2cClock(1); // set up for transition
hali2cWait(1);
OCM_DATA_LOW(); // start
hali2cWait(1);
hali2cClock( 0 );
}
/*********************************************************************
* @fn hali2cRead
* @brief Toggle the clock line to let the slave set the data line.
* Then read the data line.
* @param void
* @return TRUE if bit read is 1 else FALSE
*/
STATIC _Bool hali2cRead( void )
{
// SCL low to let slave set SDA. SCL high for SDA
// valid and then get bit
hali2cClock( 0 );
hali2cWait(1);
hali2cClock( 1 );
hali2cWait(1);
return OCM_SDA;
}
/*********************************************************************
* @fn hali2cStop
* @brief Terminates SM-Bus communication. Waits unitl the data line
* is low and the clock line is high. Then sets the data line
* high, keeping the clock line high to stop I/O.
* @param void
* @return void
*/
STATIC void hali2cStop( void )
{
// Wait for clock high and data low
hali2cClock(0);
OCM_DATA_LOW(); // force low with SCL low
hali2cWait(1);
hali2cClock( 1 );
OCM_DATA_HIGH(); // stop condition
hali2cWait(1);
}
/*********************************************************************
* @fn hali2cClock
* @brief Clocks the SM-Bus. If a negative edge is going out, the
* I/O pin is set as an output and driven low. If a positive
* edge is going out, the pin is set as an input and the pin
* pull-up drives the line high. This way, the slave device
* can hold the node low if longer setup time is desired.
* @param dir - clock line direction
* @return void
*/
STATIC void hali2cClock( bool dir )
{
if ( dir )
{
IO_DIR_PORT_PIN( OCM_CLK_PORT, OCM_CLK_PIN, IO_IN );
while(!OCM_SCL) /* Wait until clock is high */
hali2cWait(1);
}
else
{
IO_DIR_PORT_PIN( OCM_CLK_PORT, OCM_CLK_PIN, IO_OUT );
OCM_SCL = 0;
}
hali2cWait(1);
}
/*********************************************************************
* @fn hali2cWrite
* @brief Send one bit to SM-Bus device
* @param dBit - data bit to clock onto SM-Bus
* @return void
*/
STATIC void hali2cWrite( bool dBit )
{
hali2cClock( 0 );
hali2cWait(1);
if ( dBit )
{
OCM_DATA_HIGH();
}
else
{
OCM_DATA_LOW();
}
hali2cClock(1);
hali2cWait(1);
}
/*********************************************************************
* @fn hali2cClock
* @brief Clocks the SM-Bus. If a negative edge is going out, the
* I/O pin is set as an output and driven low. If a positive
* edge is going out, the pin is set as an input and the pin
* pull-up drives the line high. This way, the slave device
* can hold the node low if longer setup time is desired.
* @param dir - clock line direction
* @return void
*/
STATIC void hali2cClock( bool dir )
{
if ( dir )
{
IO_DIR_PORT_PIN( OCM_CLK_PORT, OCM_CLK_PIN, IO_IN );
}
else
{
IO_DIR_PORT_PIN( OCM_CLK_PORT, OCM_CLK_PIN, IO_OUT );
OCM_SCL = 0;
}
hali2cWait(1);
}
/*********************************************************************
* @fn hali2cSendByte
* @brief Serialize and send one byte to SM-Bus device
* @param dByte - data byte to send
* @return ACK status - 0=none, 1=received
*/
STATIC _Bool hali2cSendByte( uint8 dByte )
{
uint8 i;
for ( i = 0; i < 8; i++ )
{
// Send the MSB
hali2cWrite( dByte & 0x80 );
// Next bit into MSB
dByte <<= 1;
}
// need clock low so if the SDA transitions on the next statement the
// slave doesn't stop. Also give opportunity for slave to set SDA
hali2cClock( 0 );
OCM_DATA_HIGH(); // set to input to receive ack...
hali2cClock( 1 );
hali2cWait(1);
return ( !OCM_SDA ); // Return ACK status
}
