PIC18LF13K50 Extremly low power counter

[ScaleRobotics]

Thanks Jerson,

The main reason I ask is I think it would make a great little Wiki with some time/power results. I don't recall seeing anything like that on the forum. If there is not an interest here, then I will try working something up.

Walter

[prstein]

Can any of you folks share how you measure the average current draw? I've done a few extremely low power projects and have always sort of "eyeball averaged" the current on a standard multimeter. I'd love to learn a better method.

Best Regards,
Paul

[mackrackit]

I use a Fluke 83. It has a MIN/MAX button.

[Jerson]

Well almost all the folks who have tested use a multimeter to check. The benchmark is the datasheet which would show a typical draw of 40uA. Anything over that indicates something is drawing power and you need to check on it. I've listed some of the tricks that I used.

This is the code I use that puts the PIC into low power sleep

StopNow:
        
        PORTB = $f8         ' turn all rows low for interrupt to occur
        INTCON = $8         '  RBIE = 1 to wakeup from sleep, not necessary to have GIE enabled for this
asm
        sleep
        nop                      ' the 2 nops are a workaround for some pics 
                                   ' that slip on the  sleep
        nop
endasm

        PORTB = $ff         ' turn off all rows
        INTCON = 0         ' turn off the interrupts as I don't need them now
        goto  loopstart     'start right at the front

Besides this, things like BOR, Watchdog all consume power. You should consider if your application needs these features more than the minimized power drain.

Check each pin of the PIC to see that it is turned to a state which does not cause power drain due to itself or connected circuitry. For example, if you have the PORTB pullups turned on, putting a PORTB pin to 0 will cause a current drain there. Turning the port to all inputs may not be the best solution always.

[LinkMTech]

Can any of you folks share how you measure the average current draw? I've done a few extremely low power projects and have always sort of "eyeball averaged" the current on a standard multimeter. I'd love to learn a better method.

Best Regards,
Paul

Hi Paul,
I used to use this meter for the low current stuff:

But just as Jerson outlined the necessary steps and precautions of putting that baby to Sleep, I saw the current drop off the bottom edge, now that was exciting!
I bought the Fluke 8050A that can measure into the 10's of nano Amps to see what was really happening.

[pedja089]

scalerobotics, Here is it, but not whole code.

            define OSC 4
            'RTC
            SYMBOL SCL = PORTC.3
            SYMBOL SDA = PORTC.6
            symbol CLCK_Alrm = portc.7
            input clck_alrm
            'Input
            symbol In1 = PORTA.1
            symbol In2 = PORTA.0
            symbol In3 = PORTA.5
            symbol In4 = PORTC.5
            INPUT PORTA.1
            INPUT PORTA.0
            INPUT PORTA.5
            INPUT PORTC.5
            'Pull
            symbol Pull= PORTA.4
            OUTPUT Pull
            output portc.4 'just for testing
            OSCCON=%01010110
            OSCCON2.2=0
            ANSEL=0            
            ANSELH=0           
            SLRCON=0           
            RCON.7=1   

            UCON.3=0       ' disable usb, to alow use of ra0 and ra1
            IOCA=3         ' set ioc on ra0 and ra1 EDIT: bits 0 and 1 must be set, to use ra0, ra1...
        
            INTCON=0  
            INTCON2=%10000000  
            INTCON3=%00000000  
            PIR1=0
            PIR2=0
            PIE1=0
            PIE2=0
            IPR1=0
            IPR2=0

    

            
disable
PWR_On:                                       
pause 10
I2CWrite sda,scl,$a2,$02,[1,1,1,1,1,1,1]    ' just put some valid time/date in rtc
I2CWrite SDA,SCL,$A2,1,[%00000010]
I2CWrite SDA,SCL,$A2,$0D,[%10000010]        'enable clockout @ 32Hz
enable
INTCON=%10010000                            'enable interrapt's
on interrupt goto int


Start:
sleep 60                'sleep until int0                    
goto start 
disable interrupt

Int:
pull=1 'enable pull up
Toggle portc.4 'do something :)
'Read/write to portst etc.
pull=0 ' disable pull up
INTCON=%10010000 
goto start   
end

In file ppb/18F13K50.INC I'm just put OFF where ON was

        __CONFIG    _CONFIG1L, _CPUDIV_NOCLKDIV_1L & _USBDIV_OFF_1L
        __CONFIG    _CONFIG1H, _FOSC_IRC_1H & _PLLEN_OFF_1H & _PCLKEN_OFF_1H & _FCMEN_OFF_1H & _IESO_OFF_1H 
        __CONFIG    _CONFIG2L, _PWRTEN_OFF_2L
        __CONFIG    _CONFIG2H, _WDTEN_OFF_2H & _WDTPS_512_2H 
        __CONFIG    _CONFIG3H, _MCLRE_OFF_3H 
        __CONFIG    _CONFIG4L, _STVREN_OFF_4L & _LVP_OFF_4L & _BBSIZ_OFF_4L & _XINST_OFF_4L

Still I wonder why TMR0 was not stable...
Code is a similar, i just enabled tmr0osc and overflow interrupt.
Edit2: I'm using UNI-T UT81B