osccal register

[chava]

Hello
I have a pic 16f630 which I erased its calibration data( the "retlw k" instruction in address 0x3ff)


I want to re-program that location
I want that in program memory address 0x3ff will be :"retlw 0x80"

I tryed:

#org 0x3fd,0x3ff
char const cal[1]={0x80};

but this generated the code:

address 0x3fd: addwf pcl,f
address 0x3fe: retlw0x80
address 0x3ff: retlw 0x0

I tryed :
#org 0x3ff
#asm
retlw 0x80
#endasm


but the compiler asked me about a decleration ("expecting a decleration")

how can I do that?

[Doug]

If 0x80 is the factory calibration value then you can put this at the top of your program:

[Guard]

hi,

Does the program function if retwl dosn't exist ? ( I erased all memory ) ???

[Mark]

If you use the internal OSC and that location is blank, then no. It will just loop. It expects a return there. The instuction will act as a NOP and the PC will roll to 0 and the program start over. Most programmers protect this space and won't even allow you to save to it.