How to use ALL 876 outputs?

[June85]

Hi, I trying to use PIC16F876 to light on 16 LEDs. But I can maximum light on 7 LEDs. I already connected all B0-B7 and C0-C7 to 1Kohm resistor. But still not working.

I doubt it maybe caused by lack of power for all the LEDs. Anybody can help me to solve it? Thanks...
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This message was ported from CCS's old forum
Original Post ID: 144515232

[Haplo]

There is a limit on the current that PORTB & PORTC can source/sink. Consult the datasheet for the actual value (I think it is 200mA). You probably need to buffer your LEDs.

Ali
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This message was ported from CCS's old forum
Original Post ID: 144515233

[R.J.Hamlett]

:=
:=Hi, I trying to use PIC16F876 to light on 16 LEDs. But I can maximum light on 7 LEDs. I already connected all B0-B7 and C0-C7 to 1Kohm resistor. But still not working.
:=
:=I doubt it maybe caused by lack of power for all the LEDs. Anybody can help me to solve it? Thanks...

With 1K resistors you should be OK. You say 'resistor' - hopefully you mean 'resistors'... Operation also depends on how much power your circuit can deliver.
If you have each output connected to a resistor, and then to an LED, the current required, will only be in the order of 3mA for each LED. The chip can happily deliver this. However your supply, will have to deliver nearly 50mA more when the LED's are all on, than with them off.

Best Wishes
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This message was ported from CCS's old forum
Original Post ID: 144515250