lpc1768_pclkValue.c

unsigned int getPrescalarForUs(uint8_t timerPclkBit)
{
    unsigned int pclk,prescalarForUs;
    pclk = (LPC_SC->PCLKSEL0 >> timerPclkBit) & 0x03; /* get the pclk info for required timer */

    switch ( pclk )                                   /* Decode the bits to determine the pclk*/
    {
    case 0x00:
        pclk = SystemCoreClock/4;
        break;

    case 0x01:
        pclk = SystemCoreClock;
        break; 

    case 0x02:
        pclk = SystemCoreClock/2;
        break; 

    case 0x03:
        pclk = SystemCoreClock/8;
        break;
    }

    prescalarForUs =pclk/1000000 - 1;                 /* Prescalar for 1us (1000000Counts/sec) */

    return prescalarForUs;
}