Can I combine outputs for more current?

[Ron Marcus]

I have used multiple outputs to run small motors up to 200mA(The maximum chip rating) with little problem. Let's see your code for turning the LED on, and, how are you limiting the current through the LED?

You do know that it would be better to run the LED with a transistor capable of the total current than a couple of pins from the PIC.

Try turning the port pins on as a whole. As in... PORTA = %000011, as opposed to individual pin switching. Also keep in mind, the PIC would rather pull to ground, than to B+.

Hope this helps,
Ron

[jswayze]

Here is my code for the whole program. Basically it switches two outputs based on the pulse width of two incoming signals.

' ---------------------------------------------
' Define aliases to the LED ports
' ---------------------------------------------
PWM1 var GPIO.0
PWM2 var GPIO.1
IO1A var GPIO.2
IO1B var GPIO.5
IO2 var GPIO.4


PwmCount1 var byte               ' Count number of cycles for PWM1
PwmCount2 var byte               ' Count number of cycles for PWM2

     INTCON.6=0                 ' Disable all unmasked Interrupts
     INTCON.7=0                 ' Disable Global Interrupts
     CMCON = 7
  
    '------------------------------
    ' Main program starts here
    '------------------------------

    input PWM1
    input pwm2
output IO1A
output IO1B
output IO2
    
    pwmcount1 = 0            ' Initialize PWM counter variables
    pwmcount2 = 0       

MAIN:  

pulsin pwm1,1,PwmCount1
PULSin pwm2,1,PwmCount2
if Pwmcount1 > 140 then
   IO1A = 1
   IO1B = 1
   else
        IO1A = 0
        IO1B = 0
endif

if Pwmcount2 > 140 then
   IO2 = 1
   else
       IO2 = 0
endif
              
        goto MAIN   'endless loop

END

I will try switching IOA and IOB simultaneously and see if that works.

Thanks,

Jeff

[jswayze]

Actuating the two output simultaneously seems to have done the trick. I used "GPIO = GPIO and %00100100" to turn them on and everything works as expected now.

I have another general question regarding power switching, but I'll open a new thread. Thanks for the help!

Jeff