? about sleep/wake on pin change and WDT

[Jerson]

Kessral

If I understand you correctly, you want to do a pulsout (1) every time the PIC is woken by the magnetic switch. Waking on a magnetic switch can be done by a pin change interrupt, if available in the 10F(Havent used, so I cant comment on this). So, your ideal work loop will be something like

while (1)
PULSOUT pin, period
@ SLEEP
@ nop
@ nop
' on waking from interrupt, go back to pulsout
wend

Of course, I haven't shown the part needed to configure the PIC for interrupt on change, etc

Jerson

[kessral]

No Jerson, I'm trying to get it to pulsout as the main function every few seconds or so. I want it to sleep as if it were turned off. And then continue its normal function pulsing when awakened.

I have tried your suggestion tho Bruce and come up with this code:

__________________________________________________ ____________

TRISIO=%11111111
STATUS=%10010000
OPTION_REG=%00001000
check var bit
Low GPIO.0

loop:

nap 4
pulsout 0, 4000
nap 5

IF GPIO.1 = 1 then
suspend:
pause 2000
check = GPIO
sleep 65535
IF GPIO.1 = 1 then
goto loop
else
goto suspend
endif
endif

goto loop
__________________________________________________ _____________

This seems to work. It wakes and sleeps on pin change just fine... however my problem now is that its drawing some 60uA instead of the 5-10uA listed in the datasheet. I'll keep looking through to see if there is something else I can do to lower the current drain, but for now this seems to be as close as I am going to get.

I DID notice however that GPIO 3 is constantly high... this could have something to do with current drain being slightly higher so that is what I am currently looking into.

Again thanks for the Input guys.

P.S. This is on a PIC10F202 and I am using MPLAB IDE v7.11

[skimask]

No Jerson, I'm trying to get it to pulsout as the main function every few seconds or so. I want it to sleep as if it were turned off. And then continue its normal function pulsing when awakened.

I have tried your suggestion tho Bruce and come up with this code:

__________________________________________________ ____________

TRISIO=%11111111
STATUS=%10010000
OPTION_REG=%00001000
check var bit
Low GPIO.0

loop:

nap 4
pulsout 0, 4000
nap 5

IF GPIO.1 = 1 then
suspend:
pause 2000
check = GPIO
sleep 65535
IF GPIO.1 = 1 then
goto loop
else
goto suspend
endif
endif

goto loop
__________________________________________________ _____________

This seems to work. It wakes and sleeps on pin change just fine... however my problem now is that its drawing some 60uA instead of the 5-10uA listed in the datasheet. I'll keep looking through to see if there is something else I can do to lower the current drain, but for now this seems to be as close as I am going to get.

I DID notice however that GPIO 3 is constantly high... this could have something to do with current drain being slightly higher so that is what I am currently looking into.

Again thanks for the Input guys.

P.S. This is on a PIC10F202 and I am using MPLAB IDE v7.11

Have you got any pullup or pulldown resistors in there anywhere?
5v / 10k = 500uA
And the datasheet does say that the weak pull up current is 250uA average.
Just a couple of ideas for ya...

[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.