12F629 Wakes only once

[Bruce]

Strange. This works precisely as expected. No matter how many times I press/release the
switch.

@ DEVICE MCLR_OFF, INTRC_OSC_NOCLKOUT, WDT_OFF, BOD_OFF, PWRT_ON, PROTECT_OFF
DEFINE OSCCAL_1K 1

CMCON = 7
TRISIO = %001100
OPTION_REG = %01000000
GPIO = 0
T1CON = 0

'GPIO.0 =
'GPIO.1 = LED HIGH OUT
'GPIO.2 = SWITCH HIGH INPUT
'GPIO.3 = MCLR TIED HIGH
'GPIO.4 =
'GPIO.5 =

Main:
    HIGH GPIO.1 
    PAUSE 1000
    LOW GPIO.1 
    
    INTCON.1 = 0
    INTCON.4 = 1
    FLAGS = 0
    @ SLEEP
    @ NOP
    
    INTCON.1 = 0
    HIGH GPIO.1
    PAUSE 100
    LOW GPIO.1
    
    INTCON.1 = 0
    INTCON.4 = 1
    FLAGS = 0
    @ SLEEP
    @ NOP
    HIGH GPIO.1
    PAUSE 1000
    GOTO Main
    
    END

10K pull-down to ground on GPIO.2 with switch pulling it to Vcc on press.

[jderson]

Strange indeed. I programmed my part with your program using cut & paste, and my results are the same as they were, no second operation! It must be some sort of hardware anomaly. I will chase it with my scope later.

[Bruce]

Try setting bit 7 in OPTION_REG to disable internal pull-ups. WPU powers-up with all internal
pull-ups enabled, and with OPTION_REG = %01000000 you'll have internal pull-ups ON.

I suspect it works on mine due to a slight difference in the internal pull-up. That should cure
it unless you have a problem with your switch circuit.

[nomad]

trying to use "temp = GPIO.2" without declaring the temp variable is probably your syntax error.

"temp var byte" (word whatever) near/at the beginning would solve that.

[jderson]

Thanks for your help, guys! OPTION_REG = %1100000 solves the problem. But why does it work the first time, and not the second time????

[Pic2008]

Sounds weird to me, have you tried using another chip, is it the same result too?

[jderson]

Mystery solved: My homemade development board has 3 other PIC sockets, 2 of which are occupied with 2 different PICs, running different programs. All of these parts share the same switch. This switch has a 5K resistor to ground, and pulls to +5V. The 16F688 has it's external interrupt pin connected to the switch, and also had it's internal pullups enabled. With only the 12F629 attached (internal pullups enabled), the voltage on the INT pins was +1V. With both PICS attached, the voltage rises to +2V. The external interrupt pins are Schmitt trigger inputs. The data sheet says the minimum voltage for "a 1, or a high" is 0.8V.
So the 12F629 was seeing a high when it should have been a low. I have the software set to trigger on the rising edge of the switch, so it went HIGHER, LOWER, and then HIGHER. With both PICS having their internal pullups disabled, the voltage is now +2mv, and all is well. So much for "weak" pullups! As usual, I learned a lesson. Thanks to everyone for your help.