8-bit MicrocontrollersのトピックRe: problem with internal oscillator

problem with internal oscillator

Daxx — Thu, 14 Sep 2006 03:24:32 GMT

Hi everybody!

I have a problem with the internal oscilator, I've tried to change the value of the bus frecuency using the value of the OSCTRIM register, but nothing happened. Here is some code:

MOV   #1,CONFIG1
            MOV   #-1,OSCTRIM
            LDA   #-1
herei:   DBNZA here

The delay is for wait establishment of the internal oscillator.

am I doing something wrong?

do you really think that I can trust in the internal oscillator?

I'm using Code Warrior V 5 and a microcontroller of Q family.

Re: problem with internal oscillator

Daxx — Thu, 14 Sep 2006 03:34:57 GMT

Sorry, the "i" in label "herei", does not suppose to be there

Re: problem with internal oscillator

bigmac — Thu, 14 Sep 2006 10:11:45 GMT

Hello Daxx,

For the QT/QY series, the trim value to be written to the OSCTRIM register will be found at the flash location $FFC0, unless it has been erased (a value of $FF). You appear to be writing a constant value of $FF (= -1) to the register, which would be an extremity of the adjustment range. The centre value of the adjustment range is $80.

The following code snippet would be more typical of the trim adjustment process, usually done during initialisation, where

TRIMVAL EQU $FFC0

         LDA    TRIMVAL
         CMP    #$FF           ; Test for unprogrammed value
         BNE    ST2            ; Branch if programmed
         LDA    #$80           ; Nominal default trim value
ST2:     STA    OSCTRIM

On power-up the MCU will default to the internal oscillator, so there is no need for any stabilization delay.

Regards,

Mac

Re: problem with internal oscillator

Daxx — Sun, 17 Sep 2006 07:56:21 GMT

hi bigmac, thanks for answer to my cuestion.