I recently moved a project to a PIC18F46K22 and am getting some unexpected
results when using various pins as outputs. The data sheet says:

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- High-Current Sink/Source 25 mA/25 mA

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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 pin
to ground (VSS) nothing happens but an LED indicates the port goes high. Of
course the device polarity is adjusted for each situation.

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I tried PORTD because ports A and C have a lot of other things going on and
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.

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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 thi=
s
kind of operation.

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I can work with the ports as source only but this seems contrary to the dat=
a
sheet which explicitly says Sink/Source.

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What am I missing here?

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Allen

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