10F222 Wake on pin change

[AvionicsMaster1]

Ladies and Gents,
For some reason I keep trying to use smaller PICs instead of larger. My query today is about the Wake-on-pin change feature of the 10F222 and how to implement it.

I've got this program that while sleeping is pulling around 3uA at 6ish volts which is pretty good but I want, well, less. I'm not using a voltage regulator and am feeding 4 x AAA battery voltage to the circuit/PIC. My question is, is this the correct way to implement a wake on pin change? I think this is just a loop that naps alot and that's why it uses so little power not a wake on pin change.

clear

define OSC 4 ' if changed make sure to change config statement
adcon0 = 0         ' Turn off ADC
option_reg = %01000000 ' 7 = !GPWU wake on pin change. 6 = !GPPU weak pull up 
status = 0
osccal = %00000000  ' oscillator calibration
trisio = %1000      ' All but GP3 is output
gpio = 0

#CONFIG
       __config _IOFSCS_4MHZ & _WDT_ON & _MCLRE_OFF & _CP_OFF
#ENDCONFIG


GREEN var gpio.1             '-----------------------------variables and constants
RED var gpio.0
BLUE var gpio.2
SWITCH VAR GPIO.3 
state var byte

start_here:                  ' ------------------------------finally the program
state = gpio  ' read the gpio ports
adcon0 = 0 ' I read somewhere that after a reset you need to set this register again
nap 5
if switch = 0 then gosub light_LED ' looking for the button
goto start_here

light_led:         '-----------------------------------------------------led sub

red = 1            
pause 1000
red = 0
green = 1
pause 1000
green = 0
blue = 1
pause 1000
GREEN = 1
red = 1
pause 1000
GPIO = 0

return

END

I didn't add a schematic so I hope a word picture will do. The LED cathodes are connected to ground and the anode to a resistor, forget size, and the resistor to PIC port pins. The switch is between the PIC and ground. I know I could get lower current if I used a slower oscillator but that will take up two pins leaving me only 1 output pin. My ultimate goal is to have this battery powered device sit on the shelf for a very long time without having to change the batteries.

I'd appreciate some learning if someone would be willing to part with it.

[HenrikOlsson]

Hi,
When using the NAP command the PIC goes to sleep, for a while, wakes up, goes to sleep, wakes up and so on, keeping track of how many "cycles" in order to give you roughly the amount the sleeptime you tell it to. It uses the WDT to do this.

Using Wake-on-change will put the PIC to sleep and it'll stay there until a change occurs. I've never used the feature and I've never used the 10F parts but it looks like all you need to do is enable GPWU (like you are doing). Then when you're ready to go to sleep you do a read of the GPIO register to get the current state and then put the chip to sleep using the assembly instruction SLEEP (not the PBP command) ie, @ SLEEP

At this point the PIC will go to sleep until a change occurs on one of the GPIO pins which are set to be inputs. I think that you'll have to disable the WDT otherwise IT will timeout and Wake the PIC up.

start_here:                  ' ------------------------------finally the program
   adcon0 = 0 ' I read somewhere that after a reset you need to set this register again
   state = gpio  ' read the gpio ports
   if switch = 0 then gosub light_LED ' looking for the button
@ SLEEP
goto start_here

Again, I've never actually tried this, just read the datasheet so take it for what it is.

With that said I really wouldn't want to run it at anything above 5.5V......

/Henrik.

[gadelhas]

Hi;

Here is a program that i wrote in the past.

'****************************************************************
'*  Name    : Temporizador 3m p/ Lavar Dentes.BAS               *
'*  Author  : gadelhas                                          *
'*  Notice  : Copyright (c) 2012 ProSystems                     *
'*          : All Rights Reserved                               *
'*  Date    : 01-03-2012                                        *
'*  Version : 1.0                                               *
'*  Notes   : Proteus + Circuito com SOT-23 e CR2032            *
'*          : 10F222 - Wake from sleep através de IOC no GP3    *
'****************************************************************
@ __config _IOFSCS_4MHZ & _WDT_OFF & _MCLRE_OFF & _CP_OFF & _MCPU_ON

 DEFINE OSC 4

 '===================SRF AND PINOUT CONFIGURATION - 1-In / 0-Out=================
              '76543210
     TRISIO = %00001000
       GPIO = %00000000
 OPTION_REG = %00000000 'OPTION_REG.7 - Wake on change bit 0=Enable
     ADCON0 = %00000000 'Analog pins disable

'==================================ALIAS========================================
 VAZIO1 VAR GPIO.0
 VAZIO2 VAR GPIO.1
 LED    VAR GPIO.2
 MCLR   vAR GPIO.3
 GPWUF  var STATUS.7
 
'=================================VARIABLES=====================================
 I VAR BYTE
 C VAR BYTE: C = 0
 
'================================MAIN LOOP======================================
@ movlw 0x01A  ;OSCCAL Value
@ movwf OSCCAL

 IF GPWUF = 0 THEN DESLIGA  'Test what caused the Reset
 
Main:

 WHILE MCLR = 0    'If button pressed for 3 seconds, turn on led
    PAUSE 100
    C = C + 1
    IF C = 30 THEN LIGA
 WEND
 
 FOR I = 0 TO 119 '~120 Segundos a Piscar de 1 em 1 Segundo
    HIGH LED
    PAUSE 500
    GOSUB VERIFICA 
    LOW LED
    PAUSE 500
    GOSUB VERIFICA
 NEXT

 FOR I = 0 TO 59  '~30 Segundos a Piscar de 0,5 em 0,5 Segundo
    HIGH LED
    PAUSE 250 
    LOW LED
    PAUSE 250
    GOSUB VERIFICA
 NEXT

 HIGH LED
 FOR I = 0 TO 59  '~30 Segundos sempre ligado
     PAUSE 500     
     GOSUB VERIFICA
 NEXT
 LOW LED
  
 'Sequencia de finalização
 HIGH LED: PAUSE 100: LOW LED: PAUSE 100
 HIGH LED: PAUSE 100: LOW LED: PAUSE 100
 HIGH LED: PAUSE 100: LOW LED: PAUSE 100

DESLIGA:
 C = 0
 I = GPIO     'Must read GPIO before entering sleep. Read the Datasheet
@ SLEEP
@ NOP
GOTO Main

'================================SUB-ROUTINES===================================
LIGA:
    HIGH LED
    PAUSE 1000
    WHILE MCLR !=0
    WEND
    LOW LED
GOTO DESLIGA

VERIFICA:
 IF MCLR = 0 THEN
     C = C + 1
     IF C = 6 THEN
         'Sequencia de finalização
         HIGH LED: PAUSE 100: LOW LED: PAUSE 100
         HIGH LED: PAUSE 100: LOW LED: PAUSE 100
         HIGH LED: PAUSE 100: LOW LED: PAUSE 100
         PAUSE 1000
         GOTO DESLIGA
     ENDIF        
 ENDIF
RETURN
END

[ruijc]

With that said I really wouldn't want to run it at anything above 5.5V......

I agree...But for that you can just add a diode in series to lower the voltage down a bit.

Regards
Rui

[AvionicsMaster1]

Good idea on the diode. Thanks.

I know what RTFDS says but for what I'm doing I assume the four AAA batteries are putting out somewhat less than 1.5V and typically the four pack is close to 5.6V. After a short period they are below the 5.5V level and stay like that for a long time with only a 3uA draw. They'll last even longer if I can get it down in the nano Amp range.

I've yet to try the ASM sleep but will try soon. Thanks for ideas.

[Charlie]

Brand new batteries will actually put out more than 1.5V. I'd recommend the diode. Also helps for the day you accidentally put them in backwards. Or use NiCDs.