>>Reginald Neale wrote:
>>[snip]
>>> Why can't I tweak the internal oscillator on a 12C671/JW part? I'm using
>>> the standard header file with MPLAB and a PicStart Plus. My code is:
>>>
>>>     org     0x00
>>>     movlw   0xXX
>>>     movwf   OSCCAL
>>>
>>> But no matter what I put in for XX, the osc freq doesn't change. I must
be
>>> overlooking something pretty basic.
>>> Reg Neale



OSCCAL is in BANK1. have you selected BANK1?


>>
>>Reg - -
>>I don't program the 12C671, but the chips that I do program require
>>that the OSCCAL value be placed at the top location in memory.
>>
>>    ORG     0x1FF
>>    MOVLW   0xXX
>>    ORG     0x000
>>    MOVWF   OSCCAL
>>
>>Hope that this helps you,
>> - Nick -


Unlike the 12c508/509, the instruction at the top of the address space is
retlw 0xXX, not movlw 0xXX


code_start  equ    0x05

            org    top_of_memory
            retlw  0xXX

            org    0x00                ;reset vector
            goto   code_start

code_start  bsf     STATUS, RP0        ; select BANK1
            call    top_of_memory
            movwf   OSCCAL

>
>Thanks, Nick. The top location for this part is 0x3FF. I did try that.
>Didn't seem to cause any change. Maybe I'm screwing something else up.
>
>Reg
>