Lpc2000

Have you accounted for the fact that your VPB bus is default cclk/4 ?
(Pclk).
You set this at register VPBDIV.

-- Kris

----- Original Message -----
From: "manikandan palaniappan" <aravindar_manikandan@...>
To: "Leon Heller" <leon.heller@...>; <leon_heller@...>;
<lpc2000@yahoogroups.com>
Sent: Thursday, December 02, 2004 1:13 AM
Subject: [lpc2000] Timer_interrupt


>
>
> Hi,
>
> I am using LPC 2104 with 14.7456Mhz crystal.i want a timer interrupt to be
occured every 1 minute.The calculation and settings i follwed are below
>
> I AM USING IAR EMBEDDED WORKBENCH 4.11A
>
> PLLCON = ( PLLCON & ~MA_PLLCON_SCB_MASK ) | MA_PLLCON_SCB;
>
> PLLCFG = ( PLLCFG & ~MA_PLLCFG_SCB_MASK ) | MA_PLLCFG_SCB;
>
> PLLFEED = ( PLLFEED & ~MA_PLLFEED_SCB_MASK ) | MA_PLLFEED_SCB;
>
> PEFINED VALUES
>
> PLLCON= ?
>
> MA_PLLCON_SCB_MASK=0x00000003
>
> MA_PLLCON_SCB=0x00000000
>
> PLLCFG=?
>
> MA_PLLCFG_SCB_MASK=0x0000007F
>
> MA_PLLCFG_SCB=0x00000000
>
> PLLFEED=?
>
> MA_PLLFEED_SCB_MASK=0x000000FF
>
> MA_PLLFEED_SCB=0x00000000
>
> I DID'NT FIND ANY VALUES FOR PLLCON,PLLCFG,PLLFEED.WHEN CALCULATING WITH
DEFAULT VALUE FOR PLLCON,PLLCFG,PLLFEED AT RESET,I THINK PLL IS DISABLED AND
MY SYSTEM RUNS AT 14.7456Mhz only
>
> TIME PERIOD T=1/F
>
> T=1/14745600
>
> T=67.8 nano seconds
>
> for timer counting upto FFFF FFFF it takes 67.8e-9 * 0xFFFF FFFF,it gives
me 287 seconds.whether method i followed to calculate the timer is correct
or not.for one minute timer interrupt the calculation is
>
> 60/67.8e-9=0x34BF 5A68
>
> when i set the above value for match register 0(MR0).interrupt wont occur
at 1 minute,instead interrupt occurs at 4 minute.is my calculation and
settings are right?
>
> whether pll is disabled or not.please help me to set correct settings and
calculation.
>
> rgds,
>
> mani
>
>
>
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