I use the outputs on 18F24K22 (same family) and other PICs regularly to=20
drive currents much higher than 7ma without issue.  Few thoughts...

- Did you remember to change the pins on the buzzer so the PIC is=20
driving the positive side?
- Did you measure the current on that pin when it should be driving the=20
buzzer, and the voltage across the buzzer to see if it indicates what=20
may be happening?
- I assume the LED has it's own current-limiting resistor such that it's=20
not pulling the buzzer down to 2-ish volts?

Also, I don't remember the spec, but I'm pretty sure that there's a max=20
recommended source/sink current for the whole port.

Cheers,
-Neil.


On 8/23/2014 10:20 PM, Allen Mulvey wrote:
> I recently moved a project to a PIC18F46K22 and am getting some unexpecte=
d
> results when using various pins as outputs. The data sheet says:
>
>  =20
>
> - High-Current Sink/Source 25 mA/25 mA
>
>  =20
>
> I tried testing various PORTA and PORTD pins by driving a small active
> buzzer which draws about 7 mA. If the device is connected from the pin to
> VCC, it screams when the pin goes low. If I connect the device from the p=
in
> to ground (VSS) nothing happens but an LED indicates the port goes high. =
Of
> course the device polarity is adjusted for each situation.
>
>  =20
>
> I tried PORTD because ports A and C have a lot of other things going on a=
nd
> I wanted to make sure I just hadn't forgotten to turn off some peripheral=
..
> PORTD is about as generic as a PIC port can be.
>
>  =20
>
> The ports seem to be operating as open collector devices like some other
> PICs I have used. I do not see anything in the documentation to suggest t=
his
> kind of operation.
>
>  =20
>
> I can work with the ports as source only but this seems contrary to the d=
ata
> sheet which explicitly says Sink/Source.
>
>  =20
>
> What am I missing here?
>
>  =20
>
> Allen
>

--=20
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