Simple program - Strange problem!

[Bruce]

Break up your delays into shorter PAUSE times so it can react to each interrupt faster, and
don't mess with INTCON.7 when using ON INTERRUPT.

PBP places a RETURN at location 4 (hardware interrupt vector), so INTCON.7 gets left clear
and this lets PBP know an interrupt needs to be serviced.

INTCON.7 is automatically set on return from your interrupt handler. If you set INTCON.7 in
your code, after ON INTERRUPT is used, PBP assumes the interrupt has already been
serviced.

See if this helps;

DEFINE    NO_CLRWDT 1
DEFINE    OSC 4
Include "modedefs.bas"
led VAR gpio.1
i VAR BYTE
X VAR WORD

@ __CONFIG _INTRC_OSC_NOCLKOUT & _WDT_OFF & _PWRTE_ON & _MCLRE_OFF & _CP_ON & _BOD_ON & _CPD_ON & _IESO_OFF & _FCMEN_ON & _WUREN_OFF
main:
  ' Initialize the processor
  TRISIO = %111000
  GPIO = 0     
  CMCON0 = 7   
  INTCON=128
  OPTION_REG =%10000111  ' RAPU = off, PS 1:256 to TMR0 (overflows in 256*256*1uS) 65.536 mS
  pcon.5=0
  pie1=0
  t1con.0=0
  i=0

ON INTERRUPT GOTO start

pause 50

check:
if gpio.5=1 then ' Takes GP0 high BUT not low
toggle gpio.0
 'pause 300      ' TMR0 will overflow long before this PAUSE is finished
FOR X = 1 TO 300 ' 300mS PAUSE in 1mS increments
   PAUSE 1
NEXT X
while gpio.5
pause 1
wend
endif

if gpio.4=1 then ' Independently working fine BUT also takes low gp.0 if it's high only
toggle gpio.1
 'pause 300      ' TMR0 will overflow long before this PAUSE is finished
FOR X = 1 TO 300 ' 300mS PAUSE in 1mS increments
   PAUSE 1
NEXT X
while gpio.4
pause 1
wend
endif

if gpio.3=1 then
gpio.2=1
 'pause 100      ' TMR0 will overflow long before this PAUSE is finished
FOR X = 1 TO 100 ' 100mS PAUSE in 1mS increments
   PAUSE 1
NEXT X
while gpio.3
pause 1
wend
TMR0=0
INTCON.5 = 1	' enable TMR0 overflow interrupt
endif

goto check

disable
start:
i=i+1
INTCON.2=0   ' clear TMR0 overflow interrupt flag bit
if i=77 then
gpio.2=0
i=0
' INTCON=128 ' INTCON.7 gets set on return from here
endif       
resume

[Megahertz]

Hey Bruce, Now if GP1 is high, and gp0 is activated via gp4, it gets high and goes low after 2 seconds appx.
If GP1 is LOW, activating GP0 via gp4 makes it high but not low.

[Bruce]

Where is GPIO.0 activated by GPIO.4?

[Megahertz]

So Sorry, My Mistake, need a redbull. I will correct my sentence:
" If GP1 is high, and gp0 is activated via gp5, it gets high and goes low after 2 seconds appx.
If GP1 is LOW, activating GP0 via gp5 makes it high but not low"

[Bruce]

Can't say what would cause that. Programmed a 12F635 here, and it works just as
expected per the code example above.

LEDs on GPIO.0, 1 and 2, and buttons on GPIO.3, 4 and 5 with pull-down resistors, and
button presses taking inputs high.

[Megahertz]

Thanks Bruce. It was the PCB track getting short. It's working fine now.