12C671 - GP3 problem

[Acetronics2]

Hi, for some reason when I check the voltage on all pins, every pin except GP3 has 5V, whereas I don't know why GP3 is showing only 0.5V. They all are held high (5V) with 10K.

.

That looks much like a fried pin ... as it is an " input only " pin ...
You have to take care of these pins ... cause there's no clamping diode to VDD : must be treated as a full CMOS input with antistatic discharges handling precautions.

Alain

[financecatalyst]

Hi, I now got a chance to come back to this problem of my pic. Apologies for the delay in updating you.
OK, I have programmed another 12C671 taking care of static discharges. Now the voltage part on GP3 is working fine. It is pulled high at 5V. But making it low does not initiate the required serout signal.
Is there something I am missing in the code to make proper use of GP3 as an input?
Thanks

[financecatalyst]

Anyone there?
Please help

[mackrackit]

I never responded because I do not see where the problem is.

Have you changed the code or configs any? If you did re-post.
Did you try clearing the WDT like Alan suggested?

Can you post a schematic or a picture of your setup?

[financecatalyst]

Hi, thanks for the reply.
I did changed the config and enabled the WDT. The code looks like this now:

DEFINE OSC 4
Define OSCCAL_1K 1
@ __CONFIG _INTRC_OSC_NOCLKOUT & _WDT_ON & _PWRTE_ON & _MCLRE_OFF & _CP_ALL
'// For PIC12C671
include "modedefs.bas"

'// Define variables
ToTx VAR GPIO.0
PAUSE 30 
'// OSCCAL=0
TRISIO = %111110 
OPTION_REG = %10001000
ToTx = 0 
INTCON=0 
ADCON0.0=0
ADCON1=7

send:
if gpio.1=0 then
serout ToTx,N2400,["G0"]
Low ToTx
pause 10
endif

if gpio.2=0 then
serout ToTx,N2400,["G1"]
Low ToTx
pause 10
endif

if gpio.3=0 then
serout ToTx,N2400,["G3"]
Low ToTx
pause 10
endif

if gpio.4=0 then
serout ToTx,N2400,["G4"]
Low ToTx
pause 10
endif

goto send
end

My circuit only gets power when any button is pressed. I can try to scan the paper after drawing the circuit or try to find a software over the net if you think the circuit could be the culprit.
But I would like to add that rest all the buttons are working fine, so I believe the circuit is ok, GP3 is connected the same way as all other pins. Even the voltage on that pin behaves the same way as on any other pin under same circumstances but no DATA OUTPUT is there.

[mackrackit]

Can you try making GPIO3 active high?

[financecatalyst]

Yes I can do it to check but I really need to find an answer to make it work Active Low. I will reply with an update with Active High.