Christian Wimmer

Problem unsing the GP32's PLL

Discussion created by Christian Wimmer on Jan 28, 2007
Latest reply on Feb 6, 2007 by bigmac

Hi @ all

I think I have a problem using the PLL.

I’m using the GP32 and want to generate the clock with the build in PLL-VCO. According to the application note AN2105:
and the errata DE0001

I designed the schematic (please see attachment).

The PLL at the GP32 is initialized with this code:

void PLL_init(void){  PCTL_PLLON = 0;          //switch off the pll    PCTL_PRE = 0;            //Prescaler Multiplier = 1  PCTL_VPR = 2;            //Power of  Two Range  PMS = 0x03D1;            //PLL Multiplier  PMRS = 0xD0;             //VCO Range Selector  PMDS = 1;                //PLL Reverence Divider    PCTL_PLLON = 1;          //turns the PLL on  PBWC_AUTO = 1;           //Automatic bandwith controll  //while(PBWC_LOCK);      PCTL_BCS = 1;            //Selects VCO as system clock};




I've coppyed it form the Aplication Note.

On my breadboard I have the problem that the GP32 needs about 2 seconds until it runs my program. It seems to long for me.

Is this time ok, or did i make a mistake?

Thanks for help.