12F675 A/D and GPIO sleep interrupt

[Archangel]

Maybe I'm not seeing the big picture . . .

SLEEP_IT: 'use asm code for sleep as pbp has a fixed period
<font color=red>GPIO = %00000000</font color>
pause 1000
INTCON.0 = 0 'clear interrupt flag if set (GPIO should do this)
@ sleep
@ nop
goto start

in your sub routine you command all GPIOs as outputs, how will it receive
the wake up?

[Bruce]

With global interrupts enabled it will wake up and jump to location 4 expecting an interrupt
handler.

Disable global interrupts. Interrupt on change will wake the PIC from sleep, then execute
the instruction after sleep without vectoring to location 4.

Read the section on Power-Down Mode (SLEEP) for details on why this happens.

[macinug]

Thanks Joe.S and Bruce.
The SLEEP routine does actually work!!

Doesn't the GPIO = %00000000 command set all pins which are outputs to 0?
TRISIO configures them as either inputs or outputs?
It could be that the GPIO commands are causing my problem though.

The problem is that the system stays in closed position if it is started in the closed position.
If the system is started in the open position it closes it (as in the start-up routine) then opens closes and sleeps as intended.

Any chance of a 2nd look?
Cheers

[Bruce]

Can you post a schematic?

[macinug]

Hi Bruce,
Here it is. Basically driving a H-Bridge with 2 inputs and an enable.
Hope this helps. The analog input and sleep interrupt is derived from one 0/12V signal, hence stepped down.
Thanks

[Bruce]

It would help if you hard part values and part descriptions along with voltage levels at
various nodes in your schematic, but what is connected to the center node entering R1?

Which state change are you expecting to wake the PIC from sleep? If you're not testing for
this before entering sleep, you have no idea what level transition causes a wake-up. May
or may not be important. Just curious.

Also, if you're just testing for 0-5V why not just use a digital input VS an A/D?

With 10-bit resolution testing for potvalue >=250 is testing for >=~1.22V. Is the voltage in
on GPIO.0 and GPIO.5 below the input threshold levels?

Note: You still need to disable global interrupts. It will jump to location 4 on the 1st wake-
up so you'll be executing code from somewhere unexpected after the 1st wake-up. If it
does make it through that somehow global interrupts will be disabled on the 2nd pass, but
it's still not going to be working like you expect.

[macinug]

Bruce,
Thanks for looking and for some good points.

The bridge voltage (R1/R2) is either 0V or 4V. I used analog as I may need to be flexible on the voltage values later on.

The sleep operation does work fine, but I have disabled global interrupt at the start now.

The problem is that GP4 sometimes goes high of its own accord on switching on. The length of time it stays on varies, after that operation is as I intended. Is this a boot up procedure I have not reckoned with?

Also, have I assembled the bytes of the 10bit A/D correctly?

Cheers