>I'm using MPLAB 4.12.12, and wrote a demo program for a 12c509a for the
>first time. The program makes a one-chip crystal controlled sq. wave
>oscillator by using 4 GPIO pins (GP0=output, GP1,GP2,GP3=input). I arranged
>for the GP1:GP2:GP3 set to select one of eight frequencies (1/10 Hz, 1, 10,
>100, 1k, 10k, 100kHz) based on input values 000 - 111.
>
>In order to test the program (which also switches dynamically between
>frequencies when inputs are changed), I need to use a pin stimulus file.
>
>I wrote the following sample ("sqwave.sti"):
>
>!12.28.99 23.15     SQWAVE.STI
>!stimulus file for SQWAVE.ASM
>CYCLE   GPIO1  GPIO2  GPIO3
>1       1      0      0
>2       1      1      1
>3       0      1      1
>4       0      0      1
>5       0      0      0
>6       1      0      0
>7       0      1      0
>8       1      0      0
>9       1      1      1
>10      0      1      0
>20      1      0      0
>30      0      1      0
>100     1      1      1
>1000    0      0      0
>
>I reset the program in MPLAB and enabled the pin stimulus file.
>
>But when I run MPLAB step-by-step, the GPIO register stays at b'0000100x'
>instead of matching the stimulus pin values I wanted.
>
>What am I missing? I went ahead and burned the eprom, and the circuit works
>exactly as intended. So there's nothing wrong with the inputs in real life.
>
>Any suggestions? This has to be a simple fix.
>
>
>================================================================
>Robert A. LaBudde, PhD, PAS, Dpl. ACAFS  e-mail: ralKILLspamlcfltd.com
>Least Cost Formulations, Ltd.                   URL: http://lcfltd.com/
>824 Timberlake Drive                            Tel: 757-467-0954
>Virginia Beach, VA 23464-3239                   Fax: 757-467-2947
>
>"Vere scire est per causae scire"
>================================================================

>At 12:33 AM 12/29/99 -0600, John wrote:
>>I think the designation of the pins is GP1, GP2
>>and so forth.
>>
>> >I wrote the following sample ("sqwave.sti"):
>> >
>> >!12.28.99 23.15     SQWAVE.STI
>> >!stimulus file for SQWAVE.ASM
>> >CYCLE   GPIO1  GPIO2  GPIO3
>> >1       1      0      0
>> >2       1      1      1
>
>Thanks, John. The "GPIO" version was a relic of my trying everything to
>get this to work.
>
>Now, with GP1-GP3 as pin names AND all comments removed, the inputs do
>seem to be appearing at the GPIO port register! Ta-Dah!
>
>However, now I've got a new problem. Although I've configured ~MCLR off,
>
>         __CONFIG   _CP_OFF & _WDT_OFF & _MCLRE_OFF & _XT_OSC
>
>MPLAB continues to go into reset whenever GP3 goes low. The 12c509a burned
>with the program works correctly, though.
>
>Any suggestions as to how to deal with this? MPLAB apparently won't give
>up on GP3 being ~MCLR instead of an input pin.