I think I posted this too soon. I'm writing it off as a fried PIC. I've use=
d
this device for a lot of experiments recently, sometimes pushing the limits=
..
On at least one occasion I connected the buzzer in reverse polarity.

The PIC now also has the following aberration:

sbit relay at LATA2_bit;
sbit buzz  at LATA3_bit;
relay =3D 1;
then setting buzz =3D 1; resets relay to zero. I have never had an sbit
variable affect anything other than its own bit. I'm pretty sure I fried th=
e
PIC. I'm going to be busy for a few days but when I get a chance I'll try a
different PIC.

Thanks for your suggestions and comments,
Allen
Ps: I don't know where all the white space in my post came from. I leave on=
e
blank line between paragraphs.

> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf
Of
> Allen Mulvey
> Sent: Saturday, August 23, 2014 10:20 PM
> To: 'Microcontroller discussion list - Public.'
> Subject: [PIC] Port Behavior
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> 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:
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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
this
> kind of operation.
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> I can work with the ports as source only but this seems contrary to the
data
> sheet which explicitly says Sink/Source.
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> What am I missing here?
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> Allen
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> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist


--=20
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