Lpc2000

At 12:22 AM 11/23/03 +0000, you wrote:
>I just added some code to the Rowley LED flasher example to set up the PLL
>for 60 MHz operation; it looks as though it is running six times faster,
>judging by the LEDs. I filched it from some other code someone sent me that
>he's written for his own hardware, based on the Ashling board circuit.
>Here's the routine, if anyone else wants to try it:



>  *pllCFG   = 0x25;  // P = 2, M = 6
>  *pllCON   = 0x01;  // Enabling PLL but not connecting it
>  *pllFEED  = 0xAA; // Actualising the setting
>
>  for(i=1;i<10;i++);   // waiting
>
>  *pllFEED  = 0x55; // Actualising the setting
>
>  while ( !(*pllSTAT & 0x0400) ) ; // waiting for PLL lock
>
>  // connecting PLL
>
>     *pllCON   = 0x03;  // Enabling PLL but not connecting it
>     *pllFEED  = 0xAA; // Actualising the setting
>     for(i=1;i<10;i++);   // waiting
>     *pllFEED  = 0x55; // Actualising the setting
A question Leon.  Why did you put the delay in between the writes to pllFEED?

Heres an alternative (it's what I am using).

void init_pll( void)
  {

         /* set pll divisor, multiplier */
  PLLCFG = 0x25;         /* MSEL = 5 --> M = 6, PSEL = 1 --> P = 2       */
                         /* cclk = M*Fosc = 60,000,000                   */
                         /* Fcco = cclk * 2 * P = 240,000,000            */
         /* enable pll */
  PLLCON = 1;            /* Enables PLL                                  */
  PLLFEED = 0xAA;        /* Change to setting above.  These two updates  */
  PLLFEED = 0x55;        /* MUST occur in sequence on the VPB bus.       */

         /* wait for lock */
  while( (PLLSTAT & 0x400) == 0) {
     }

         /* connect pll */
  PLLCON = 3;            /* Enables and connects PLL                     */
  PLLFEED = 0xAA;        /* Change to setting above.  These two updates  */
  PLLFEED = 0x55;        /* MUST occur in sequence on the VPB bus.       */
  }

Robert Adsett