/* Config the slave select pins of the specified SPI port. 
The  */
void SPISSConfig(unsigned long ulBase, unsigned long ulSSTriggerMode, unsigned long ulSSActType)
/* Config the slave select pins of the specified SPI port. 
The  */
void SPISSConfig(unsigned long ulBase, unsigned long ulSSTriggerMode, unsigned long ulSSActType)
{
    xASSERT((ulBase == SPI0_BASE) || (ulBase == SPI1_BASE)||
            (ulBase == SPI2_BASE) );
    xASSERT((ulSSTriggerMode == SPI_SS_EDGE_TRIGGER) || 
            (ulSSTriggerMode == SPI_SS_LEVEL_TRIGGER));
    xASSERT((ulSSActType == SPI_SS_ACTIVE_LOW_FALLING) || 
            (ulSSActType == SPI_SS_ACTIVE_HIGH_RISING));
    xHWREG(ulBase + SPI_SSR) |= ulSSTriggerMode | ulSSActType;
}