wakeup initialization and PD

TheRac25 · 2007-11-20 14:21

ok so im trying to figure out how to run some code at powerup but not every time a wakeup happens
ive been trying to figure this out for a week
this should work but led just flickers and stays on a wakeup, its like im getting two wakeups in a row with the second one having PD = 1
if i set another led to = PD then it stays off so why does the code in the if statement execute?
can anyone tell whats wrong here?

DEVICE SX28, OSCHS2, TURBO, STACKX, OPTIONX
FREQ 50_000_000
led PIN RA.3 OUTPUT
PROGRAM Start NOSTARTUP
Start:
  IF PD = 1 THEN
    led = 1
  ENDIF
  
  WKED_B = %1111_1111
  WKPND_B = %0000_0000
  WKEN_B = %1111_1110
  SLEEP

RB.0 is connected to channel A of an optical encoder with 10K pullup
chip is SX28AC/DP marked ubicom
-Ben

Bean · 2007-11-20 14:49

Ben,
· Set WKPND_B after you set WKEN_B (note that you need something between the WKPND_B and SLEEP, a NOP will do).

· Also, if you are running from the IDE, it does strange things with the PD and TO bit. I can't remember right off hand, I think it never sets PD.

··I don't know if you realize that all pins are set to INPUT at wake-up. Because you have the LED defined as an OUTPUT, SX/B will make it an output again in the start-up code.

DEVICE SX28, OSCHS2, TURBO, STACKX, OPTIONX
FREQ 50_000_000
 
led PIN RA.3 OUTPUT
 
PROGRAM Start NOSTARTUP

 
Start:
  IF PD = 1 THEN
    led = 1
  ENDIF
  
  WKED_B = %1111_1111
  WKEN_B = %1111_1110
  WKPND_B = %0000_0000
  NOP
  NOP
  SLEEP

You might be getting bounce in the signal too, that would cause multiple start-ups.

What do you expect it to do ? The LED will always be on, even on a wake-up.

Bean

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Post Edited (Bean (Hitt Consulting)) : 11/20/2007 3:08:01 PM GMT

TheRac25 · 2007-11-20 15:11

ok i put an ELSE led = 0 in there and it works as expected
ill integrate this into my main code

thanks
-ben

TheRac25 · 2007-11-20 18:48

hrm ok so how do i make a pin an output without it going low->high on reset?
do i need to set it to 0 before making latch output?
i didnt realize thats what was happening

Bean · 2007-11-20 19:12

Ben,
Yeah just use "LED = 0" before the "IF PD = 1" line.

The pin doesn't actually go LOW during the wake-up. It goes to INPUT state (which of course make the LED go off).

It is the SX/B startup code that is making the pin an OUTPUT (since you have it defined that way).

Are you just experimenting or do you have a specific goal in mind ?

Bean

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·

TheRac25 · 2007-11-20 19:19

i am working on somthing specific this code is just a simplification so anyone looking doesnt have to look through all of my code

basicly this is strobing my lcd enable line every wakeup/reset, repeating the last char command since i have the lcd data linse latched on an i2c expander

my solution as of now is remove OUTPUT keywork and insert two lines at the top of Start

\· mov ra,#0
\· mov !ra,#0

doesnt apear to be strobing now

thanks for your input on this

Bean · 2007-11-20 19:49

So you don't want it to strobe at power-on, but you do want it to strobe at wake-up ?

Can you just put a pull-down or pull-up on the pin? That will hold it in the desired state during the reset (when it is in INPUT mode).

Bean.

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·

TheRac25 · 2007-11-20 20:32

i do have a pull down it was OUTPUT keyword that was making the pin high

wakeup initialization and PD

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