PIC 12F509 begins to heat at power up

[ErnieM]

Same old code, same chip, new batch of boards.
Check for a bad trace.

OR... new revision silicon is acting up (doubtful).

Interesting problem, current is going somewhere, but current isn't a directly measurable quantity suck as voltage is. Good news is you only have 6 I/O pins to check.

Depending on how repeatable the problem and how disposable a board is you could try removing one pin at a time to see who the current hog is, then seeing if you can switch on the big current if you put the offending pin back in.

One thing to check is if an INPUT is causing the problem: if an input goes to about half Vdd then it will draw a big current (thru Vdd->Vss, not the pin itself).

[Pedro Pinto]

Hello

OR... new revision silicon is acting up (doubtful).

This is always my opinion. I will order a few Pic's
to test.
The inputs are not the problem i have wired for the
tests all inputs to vcc and the problem are the same.

Regards
Pedro

[Acetronics2]

Hi, Pedro

Could you post a piece of scheme ( just around the PIC - with reset circuitry ! )

Alain

PS: in your code, you should preset your outputs ( even inputs ) BEFORE the TRIS command ...

[ErnieM]

I went thru your code a bit to count I's and O's: looks like you have two outputs.

While you wait for your chips to arrive you may want to try this: (assuming you can ICSP this board) make up some test programs, either 4 programs to try each of the two output lines high and low, or use 1 input to step thru the combos.

That way you can see if a single output being hi or low is causing the current.

Acetronics' comment about presetting GPIO's before TRIS is well taken: GPIO is undefined after a reset and perhaps a momentary state collision is occasionally taking down the power supply and ending the program right there.

Post the schematic (as much as you will).

[Pedro Pinto]

Hello ErnieM

I not preset GPIO before TRIS, i make only a alias from the pins before TRISIO

Attached the schematic

Regards
Pedro

[Archangel]

I not preset GPIO before TRIS, i make only a alias from the pins before TRISIO
Pedro

Hi Pedro,
That was the point, that you should, so when TRIS makes the port an output it does so in a state chosen by YOU, not the devil.

[Pedro Pinto]

Hello Joe S.

English is not my natural language, sorry i not understand very well what
you mean in your answer. Is anything wrong in this code?

DEFINE OSCCAL_2K 1
'
sepic_ok var GPIO.3        
call_shutdown var GPIO.4
sepic_on_off var GPIO.5
pulsador var GPIO.2
am_on_off var GPIO.1
'sense var GPIO.0
'
TRISIO = %11001111
'
low sepic_on_off        
low call_shutdown       
'						
ciclo var word
conta var byte 
conta2 var byte
flag_pulsador var byte

Do you think that i must change it? if yes, what?

Thanks
Best regards
Pedro