Re: [PIC] High Power Consumption for a Battery operated application - Electronic Safe

Francois,
I haven't gone over your Program yet, but I can make a couple of 
suggestions.

Use the slowest clock speed that will handle your application.
If you reduce your clock speed from 4 MHz to 1 MHz the PIC will consume 
only about 1/3 the power.
See Microchip 16F88 Data sheet chart 18.2

I would not enable weak pull-ups on port B. The weak pull-ups are turned 
off anyway when using the pins as outputs
Weak pull-ups only work when pins are used as inputs.

Maybe later on I may have other suggestions.

Joel T. Curneal
[email protected]


On 2025-01-07 13:14, Francois Robbertze wrote:
> Hi,
> 
> 
> 
> I need help with the power consumption on a battery operated project 
> (Keypad
> safe)
> 
> I have a lot of safes and the controllers is damaged. I want to create 
> new
> controllers for these safes and try to use what is available
> 
> 
> 
> Details: Current Power is supplied by 4xAA Batteries. Power is dropped 
> to
> 4.8 volt through 2 diodes.
> 
> 
> 
> I used PICBASIC Pro and the software works perfect except the current 
> draw
> is about 1.56mA. The datasheet show on page 167 a current draw of 1uA 
> in
> sleep mode. I use the PIC16F88. That is with the programmer 
> disconnected.( I
> measure about 156,8mV volt drop over a 100Ohm resistor )
> 
> 
> 
> What am I missing or doing wrong?
> 
> 
> 
> The Software in short:
> 
> 
> 
> Config:
> 
>     __config _CONFIG1, _INTRC_CLKOUT & _WDT_OFF & _LVP_OFF & _CP_OFF &
> _BOREN_OFF & _MCLRE_ON & _DEBUG_OFF
> 
>     __config _CONFIG2, _FCMEN_OFF & _IESO_OFF
> 
> 
> 
> Pin Setup:
> 
> Row1 VAR PORTA.0                         '4x3 Keypad
> 
> Row2 VAR PORTA.1
> 
> Row3 VAR PORTA.2
> 
> Row4 VAR PORTA.3
> 
> 
> 
> Col1 VAR PORTB.0
> 
> Col2 VAR PORTB.4
> 
> Col3 VAR PORTB.5
> 
> 
> 
> ' Other pins
> 
>     Solenoid VAR PORTA.4         ' Solenoid control pin
> 
>     Beeper VAR PORTB.3           ' Beeper control pin
> 
>     ResetButton VAR PORTB.6      ' Reset button
> 
>     Led var PORTB.2              ' heartbeat
> 
> 
> 
> Initialize:
> 
>     OSCCON = %01101110               'set int rc osc to 4mhz
> 
> 
> 
>       CMCON = 7              ' Disable comparators, PORTA as digital 
> I/O
> 
>       ANSEL = 0              ' Set all pins as digital I/O
> 
>       ADCON0 = 0             ' a to d off
> 
>       ADCON1 = 0              '??
> 
>       T1CON = 0
> 
>       T2CON = 0              ' timer 2 off
> 
>       CCP1CON = 0            ' capture compare off
> 
>       TXSTA = %00000000      '??
> 
>       RCSTA = %00000000      '??
> 
> 
> 
>       PORTA = 0              ' Initialize PORTA to 0
> 
>       PORTB = 0              ' Initialize PORTB to 0
> 
> 
> 
>       TRISA = %00000000       ' Set PORTA direction (input/output as 
> needed)
> 
>                               ' RA0 - RA3 keypad row - outputs
> 
>                               ' RA4 - stryker - output
> 
>                               ' RA5 - reset mclr - set as input
> 
>                               ' RA6 - RA7 osc
> 
>       TRISB = %01110001       ' Set PORTB direction
> 
>                               ' RB0 - col1
> 
>                               ' RB1 - nc
> 
>                               ' RB2 - LED
> 
>                               ' RB3 - Buzzer
> 
>                               ' RB4 - Col2
> 
>                               ' RB5 - Col3
> 
>                               ' RB6 - nc Programmer
> 
>                               ' RB7 - nc Programmer
> 
> 
> 
> 
> 
>       OPTION_REG.7 = 0           ' Enable weak pull-ups on PORTB
> 
>       OPTION_REG.6 = 0           ' TRIGGER INT ON FALLING EDGE
> 
> 
> 
> I then enable interrupt :
> 
> INTCON = %10011000                            ' enable change on 
> port[B4-B7]
> and ext int on port b
> 
> 
> 
> ON INTERRUPT GOTO Handleinterrupt             ' Interrupt Service 
> Routine
> 
> 
> 
> Main Routine:
> 
> 
> 
> Check for KeypressedFlag
> 
> Check for ResetPressedFlag
> 
> 
> 
> Flash LED
> 
> 
> 
> Goto Sleep:
> 
> 
> 
> OSCCON = %00000010    '32KHz
> 
> 
> 
>             asm
> 
>             sleep
> 
>             endasm
> 
> 
> 
>              OSCCON = %01101110    '4MHz
> 
> 
> 
> .and goto Main
> 
> 
> 
> Here is my Interrupt Handler.
> 
> Disable
> 
> HandleInterrupt:
> 
>     if resetbutton = 1 then
> 
>         ResetPressedFlag = 1
> 
>         resume
> 
>     endif
> 
> 
> 
>     IF INTCON.1 = 1 THEN        ' Check external INT (RB0)
> 
>         KeyPressedFlag = 1      ' Set flag for RB0
> 
>         INTCON.1 = 0            ' Clear external INT flag
> 
>     ENDIF
> 
> 
> 
>     IF INTCON.0 = 1 THEN        ' Check IOC interrupt
> 
>         'IF (PORTB & %00110000) <> %00110000 THEN
> 
>             KeyPressedFlag = 1  ' Set flag if RB4 or RB5 changes
> 
>         'ENDIF
> 
>         INTCON.0 = 0            ' Clear IOC flag
> 
>     ENDIF
> 
> 
> 
>     RESUME
> 
>     enable
> 
> 
> 
> I am currently using the PIC16F88. I tried to drop the voltage below 
> 4Volt
> with disastrous effects.
> 
> 
> 
> Should I get another PIC? . I don't want to replace the batteries every
> month.
> 
> 
> 
> Regards
> 
> 
> 
> Francois