startup.c

A2D EXAMPLE FOR LPC 2378

#include "startup.h"

void startup(void)
{
    unsigned int  m;
    unsigned int  n;
    unsigned int  clk_div;
    unsigned int  clk_div_usb;

    m           = 11;                                           /* PLL Multiplier = 20, MSEL bits = 12 - 1 = 11             */
    n           =  0;                                           /* PLL Divider    =  1, NSEL bits =  1 - 1 =  0             */
    clk_div     =  3;                                           /* Configure the  ARM Core clock div to 6. CCLKSEL =  6 - 1 */
    clk_div_usb =  6;                                           /* Configure the USB clock divider to 6, USBSEL  = 6 - 1    */

    if ((PLLSTAT & 0x02000000) > 0) 
    {                                                           /* If the PLL is already running                            */
        PLLCON  &= ~0x00000002;                                 /* Disconnect the PLL                                       */
        PLLFEED  =  0xAA;                                       /* PLL register update sequence, 0xAA, 0x55                 */
        PLLFEED  =  0x55;
    }

    PLLCON   &= ~0x00000001;                                    /* Disable the PLL                                          */
    PLLFEED   =  0xAA;                                          /* PLL register update sequence, 0xAA, 0x55                 */
    PLLFEED   =  0x55;

    SCS      &= ~0x00000010;                                    /* OSCRANGE = 0, Main OSC is between 1 and 20 Mhz           */
    SCS      |=  0x00000020;                                    /* OSCEN = 1, Enable the main oscillator                    */

    while ((SCS &  0x00000040) == 0) {                          /* Wait until OSCSTAT is set (Main OSC ready to be used)    */
        ;
    }

    CLKSRCSEL = 0x00000001;                                     /* Select main OSC, 12MHz, as the PLL clock source          */

    PLLCFG    = (m << 0) | (n << 16);                           /* Configure the PLL multiplier and divider                 */
    PLLFEED   = 0xAA;                                           /* PLL register update sequence, 0xAA, 0x55                 */
    PLLFEED   = 0x55;



    PLLCON   |= 0x00000001;                                     /* Enable the PLL                                           */
    PLLFEED   = 0xAA;                                           /* PLL register update sequence, 0xAA, 0x55                 */
    PLLFEED   = 0x55;

    CCLKCFG   = clk_div;                                        /* Configure the ARM Core Processor clock divider           */
    USBCLKCFG = clk_div_usb;                                    /* Configure the USB clock divider                          */

    while ((PLLSTAT & 0x04000000) == 0) {                       /* Wait for PLOCK to become set                             */
        ;
    }

    PCLKSEL0  = 0xAAAAAAAA;                                     /* Set peripheral clocks to be half of main clock           */
    PCLKSEL1  = 0x22AAA8AA;

    PLLCON   |= 0x00000002;                                     /* Connect the PLL. The PLL is now the active clock source  */
    PLLFEED   = 0xAA;                                           /* PLL register update sequence, 0xAA, 0x55                 */
    PLLFEED   = 0x55;

    while ((PLLSTAT & 0x02000000) == 0) {                       /* Wait PLLC, the PLL connect status bit to become set      */
        ;
    }

    
    
    /* MAM Initialize */
    MAMCR    = 0;
    MAMTIM = 3;
    MAMCR = 2;
}