12F683 Startup

[GregK]

Hi Ralph,

Thanks for your reply.

Let me explain a little more about the problem. The "Loop" is just to debug a problem I am having when I first power up the pic. The two input pins used in the program are pulled up through 10K resis. The third input pin (gpio.3) is always an input, and internally pulled up.

The problem I don't understand is why both LED's are ON when I first power up the pic, with no input pins grounded. I set the outputs Low before the "Loop" and yet they are High when I power the Pic up. I have tried other 12F683's with the same results.

Greg

[Bruce]

See if this configuration works for you. Note - you won't need the external pull-ups.

@ device pic12f683, fcmen_off, ieso_off, intrc_osc, wdt_off
@ device pic12f683, pwrt_on, mclr_off, protect_off 

GPIO = %00000000 ' All outputs low
CMCON0=7         ' Comparators off
ANSEL=0          ' All digital
TRISIO=%00111000 ' Setup ins & outs
WPU=%00110000    ' Pull-ups on for GPIO.4 & 5 inputs
OPTION_REG.7=0   ' Enable internal pull-ups

The default PBP header file for this device doesn't call-out the power-up timer (PWRT), so it defaults to off. This can cause some odd things to happen if your power supply is slow rising.

You don't need to configure ADCON0 or VRCON unless you're using A/D & comparators.

[GregK]

Hi Bruce,

I tried your changes and it works like a charm!
Now if I can get the rest of the program to work.

Thanks for your help.

Greg