12f629 problem

[John77]

after trying for two days to handle with 12f629 i've became quite
frustrated.
i used all hints and code examples found in previous posts - nothing
works .
my compiler version 3.19.
programmers : ic-prog and WinPicProg.
any help would be appreciated.
p.s with 16f73 compiler works fine.

[rwyoung]

Probably not what you want to hear, but please post short code example. COMPLETE example, #includes, #fuse, #use delay statements, etc., in other words, everything!

Also, if your compiler is reporting some errors, please list them.

Just something simple like toggle a GP I/O pin using internal oscillator only.

For example:

[Guest]

my code : (no compiles's errors)
#include <12F629.h>
#fuses INTRC_IO,PUT,NOWDT,NOPROTECT,NOMCLR, NOBROWNOUT
#use delay(clock = 4000000)


#byte CMCON = 0x19
#byte TRISIO = 0x85
#byte GPIO = 0x05

void main()
{

CMCON = 7; // Comparators off
TRISIO = 0b11111110; //0xFE;
GPIO = 0;

while(true)
{
output_high(PIN_A0);
delay_ms(1000);
output_low(PIN_A0);
}

}

[sseidman]

[Guest]

the problem is that it never goes high.

[rwyoung]

It may be going high the one time but because of the read-write-modify issue with PIC's I/O pins you might not be seeing it return high at the pin while internally it is writing a "1" to the register. What are you using to test the pin, DMM, scope, what? What kind of load do you have the pin driving?

Just for the heck of it, add a NOP (delay_cycles(1); will do it) after the output_low() and before the closing brace.

The overhead of the while loop may be sufficient but check to datasheet with reguard to the read-write-modify conditions. Should be discussed in the I/O pin description section.

Also, since you are setting the TRIS register yourself, you can add "#use fast_io(A)" to the beginning of your program.

And one last thing, check the LST file after you compile. It may be that your version of the compiler is doing something silly. I don't think I have V3.190 on my drive to test with.
_________________
Rob Young
The Screw-Up Fairy may just visit you but he has crashed on my couch for the last month!

[PCM programmer]

[Guest]

I changed the code :
while(true)
{
output_high(PIN_A0);
delay_ms(1000);
output_low(PIN_A0);
delay_ms(1000); // one more delay

}
it didn't help. scope indicates no signal on pin.
compiler version 3.190.
those programmers are reliable - code compiled in other compilers
for the same 12f629 was programmed and runs ok.

[PCM programmer]

I took your program that you posted above, suitably fixed as shown
in your later post with the additional delay_ms(1000) statement,
compiled it with vs. 3.190, and programmed it with a PicStart-Plus.
It works.

Maybe you clobbered the OSCCAL value at address 0x3FF.
Read the PIC's program memory with your programmer and
look at the value at the end of ROM. My PIC has got 0x34A8 there.
It should have a value in this format: 0x34xx

If it the value there is 0x3FFF, then you've erased the OSCCAL value.
Then the program won't run properly. The PIC will appear to be dead.

[Guest]

thank you for your concern . i'll look deeper into OSCCAL issue.