? about sleep/wake on pin change and WDT

[kessral]

I am making a device using the pic10f series microcontrollers whose main purpose is to do a pulsout every couple of seconds. I want it to pulsout and then NAP (go into low power mode between pulses for less than a second to maybe 2 seconds). This is easy.

However, I need to be able to put it to sleep and wake it up on pin change (using a magnetic switch internally sealed from elements) which requires that the WDT be disabled. I am using watch batteries (due to size restrictions) I really need for it to have the lowest power consumption possible AT ALL TIMES. NAP will not work without WDT enabled.

What else can I do, any suggestions?

[Bruce]

Use the assembler @ SLEEP option & WDT to wake up periodically and
generate your pulse. Using the prescaler you can have up to 2.3 second
sleep periods.

Use one I/O-pin to wake up on keypress, and another to enter sleep mode
when pressed.

[kessral]

Thanks for your reply but.... Unfortunately I want to be able to just wave the magnet over the switch which will change the pin state and make the pic sleep or wake. I cannot leave the magnet in place on the magnetic switch.

So I need the pic to stay sleeping after an "@ SLEEP" and not to wake at all until the pin changes when the magnet has been waved over the switch.

This means the WDT has to be disabled which kills my "NAP" or "SLEEP" usage and forces me to use pause which will not be the low power usage desired.

Anything else I could try at all?

[Bruce]

Is the magnetic switch the "only" thing that will be used to wake it up?

[kessral]

Yes, the magnetic switch will be the ony thing to wake it and tell it to sleep in this application. It should not turn on/off (wake/sleep) until a user turns it or on with the switch..

[Bruce]

Here's one scenario;

The PIC wakes up at regular intervals using the WDT. If switch = 0, then go
back to sleep. It's only awake for a few uS testing the switch.

If switch = 1, then do whatever you need to do, then test the switch input
before going back to sleep.

A switch press can also wake the PIC up before a WDT timeout. Handle
whatever you need to do, test the switch, and go back to sleep or stay
awake (resetting WDT) as required, based on the switch input.

It's still going to save a boat-load of power since it will be sleeping until your
switch is active, or the WDT times out.

If the switch isn't active, it's still alseep for the majority of time, and you'll
be operating at low current until the switch input forces the wake up, or the
WDT timeout.

Wouldn't that work?