? about sleep/wake on pin change and WDT

[kessral]

This is a good point. And I did think of this. Currently I have 1 15k pulldown to ground from the pin connected to magnetic switch to help determine high/low state.

However 60uA is not consistent with this.. I'll just have to keep it in the back of my mind, as I have many other things to get to as well, maybe I'll think of something.

[Bruce]

Try this;

DEFINE OSC 4
    
    ' GPIO.1 & 3 inputs, rest outputs. Use external pull-ups
    ' on GPIO.1 & 3.
    TRISIO=%00001010
    ' Internal pull-ups off, prescaler to wdt, 1:128 prescale,
    ' wakes up approx every 2.3 seconds.
    OPTION_REG=%01001111

    Low GPIO.0 ' pre-condition output for high pulsout

Loop: ' 100K external pull-up on GPIO.1, switch grounds GPIO.1
      ' when pressed
    WHILE GPIO.1 = 0    ' if button pressed, do pulsout
       CLEARWDT         ' reset WDT while in loop
       pulsout 0, 4000  ' pulsout GPIO.0
    WEND
    
    ' Note: It will wakeup about every 2.3 seconds on WDT timeout,
    ' or switch press, but doesn't pulsout unless switch is pressed.    
    @ SLEEP             ; else sleep
    ' Don't need goto here since wake up is a device reset.
    END

[dolphin42]

just use a inline resistor and a cap to GND on the output of your switch.

V+ --- [resistor, 10K?]----[reed switch]----[Capacitor from this line to GND]----pic I/O

The cap will "store" the switch closure event so that when the unit wakes up it can tell the reed switch was closed while it was sleeping.

The PIC can then, once it wakes up, flip the input bit to a grounded output to "reset" the circuit. Then just before SLEEP it can make the pin back into an input.

Note that if the circuit board is damp or dirty and you don't reset the circuit on every wake up from sleep, that eventually the cap can charge up.

The cap can be very small, 0.01uF (10nF) would work just fine. I tried to make
a proper ascii schematic but this forum has no code mode that I can see.