Problems starting an 18F8720

[sebastien]

High i try to start a basic blinking led, on a 18f8720, but no success, anyone knows config bits i should set to make this chip works ?

My code looks something like this.

main:
HIGH PORTA.1
PAUSE 300
LOW PORTA.0
PAUSE 300
goto main


I tried disabling WDT, HSPPL, and multiple different combinations of config bits but nothing did it.

Its not a code problem but i have no clue on how i can debug/ troubelshoot the pic, this is pre-build card with the pic and pinouts.

Should I consider that, because the pic is programmable, its most likkely not blown, i just have to find the right bits, or can it be that it's programmable but will never start because its faulty ?


Regards.

[Kamikaze47]

Have you tired disabling the analog-digital converter?

ADCON0=%00000000
ADCON1=%00001111

[sebastien]

Thanks for the reply i will give it a try when going home,
i know adcon can give unexpected behavior sometimes, but i did'nt know it can simply avoid you pic to run a simple blink led.

[Kamikaze47]

if the pin the LED is on is also an AD pin, then yes it will stop it if that pin is configured for analog use.

Also, there is a problem in your code if you want the LED to blink. HIGH PORTA.1 will put port A, pin 1 high and LOW PORTA.0 will put port A, pin 0 low and thats where they will stay. Nothing will blink.

[sebastien]

my mistake in the code i typed over, i tried with pins on almost every port.
B, H, A with the same result always. Not blinking. Therefore i have doubts over the device, how can i troubleshoot this ...

[Kamikaze47]

Hard to say without more information like the entire code, config settings and hardware setup. Are you using an external OSC?

[sebastien]

This pic is on a card with an osc onboard of 6mhz supposed to be ran on 24mhz thanks to hsppl.

Here is a pdf of the card, (it's in thai) but the last 2 pages are the wiring diagrams.

http://www.steitec.net/media/products/0000868001249723519.pdf

[Kamikaze47]

Can you post your code and config settings.

[sebastien]

Came back home and done it over again, played a bit with the config bits and it started to blink with and without adcon, one config bit i have removed was LVP .... that should not interfere execution.;.. but ok it works now thanks for the support.