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'16C73 Port A problems'
1997\07\31@221122 by Larry G. Nelson Sr.

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I have the ADCON 1 set to 04 hex and the TRIS A register configured to give
bits 4 and 5 as outputs. When I write port a with a BSF instruction I can
toggle bit 5 but not bit 4. The Simulator shows it working ok but not the
emulator. Anyone have any ideas? I already changed the Bondout chip
thinking I had a blown port. As usual these problems happen on deadline and
tend to be show stoppers.

As always any help or words of wisdom are greatly appreciated.


Larry G. Nelson Sr.
spam_OUTL.NelsonTakeThisOuTspamieee.org
http://www.ultranet.com/~nr

1997\07\31@223301 by myke predko

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Larry,

RA4 is always a Open Collector (Drain) bit.  It can never drive any kind of
voltage.

If you are driving logic, and have to use this pin, pull it up with a 1K (or
thereabouts) resistor.

Good Luck,

myke
{Quote hidden}

"If at first you don't succeed, then maybe sky diving isn't the sport for
you" - Steve Smith

1997\07\31@224103 by Larry G. Nelson Sr.

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I must be brain dead. ;) Thanks for the kick start. I knew that back when I
was getting more sleep than 4 hours a night. My FAE missed reminding me of
that one too. Thanks again.



At 10:29 PM 7/31/97 -0400, you wrote:
{Quote hidden}

Larry G. Nelson Sr.
.....L.NelsonKILLspamspam.....ieee.org
http://www.ultranet.com/~nr


'16C73 Port A problems'
1997\08\01@080333 by Joe Little
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    I had the same problem. I found out the hard way that Bit 4 is open
    drain... It can sink current, but not source any.


    >I have the ADCON 1 set to 04 hex and the TRIS A register configured to
    >give bits 4 and 5 as outputs. When I write port a with a BSF instruction I
    >can toggle bit 5 but not bit 4. The Simulator shows it working ok but not
    >the emulator. Anyone have any ideas? I already changed the Bondout chip
    >thinking I had a blown port. As usual these problems happen on deadline
    >and tend to be show stoppers.

1997\08\01@231423 by Pioneer Microsystems
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At 10:09 PM 7/31/97 -0400, you wrote:
>I have the ADCON 1 set to 04 hex and the TRIS A register configured to give
>bits 4 and 5 as outputs. When I write port a with a BSF instruction I can
>toggle bit 5 but not bit 4. The Simulator shows it working ok but not the
>emulator. Anyone have any ideas? I already changed the Bondout chip
>thinking I had a blown port. As usual these problems happen on deadline and
>tend to be show stoppers.
>
Gee, Lary, I dunno what your problem is, but how on earth did you get a
bondout chip?  I have some Microchip hardware around here that could live
again if I had their special gold plated chips.  I knew I was in trouble
when I called support and they said 'No sweat.  We'll send you another.  No
need to return the dead one.  Have a nice day.'

Chris Eddy
Pioneer Microsystems
Pittsburgh, PA

1997\08\02@005146 by Mike Smith

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---Original Message-----
From: Pioneer Microsystems <EraseMEceddyspam_OUTspamTakeThisOuTNB.NET>
To: PICLISTspamspam_OUTMITVMA.MIT.EDU <@spam@PICLISTKILLspamspamMITVMA.MIT.EDU>
Date: Saturday, 2 August 1997 12:45
Subject: Re: 16C73 Port A problems



>At 10:09 PM 7/31/97 -0400, you wrote:
>>I have the ADCON 1 set to 04 hex and the TRIS A register configured to
give
>>bits 4 and 5 as outputs. When I write port a with a BSF instruction I can
>>toggle bit 5 but not bit 4. The Simulator shows it working ok but not the
>>emulator. Anyone have any ideas? I already changed the Bondout chip
>>thinking I had a blown port. As usual these problems happen on deadline
and
>>tend to be show stoppers.
>>

This set off a lightbulb in my head - We had a similar fault, that was
reproducable across 2 different make ICE's  - Parallax and IcePic - I
contacted IcePic via email - but can't find response.  I'm *fairly* sure
they said it was a bondout chip bug.  We ended up coding around it and using
another port bit - this may not be an option for you.  BTW, is the bondout
chip a 74 or a 74A?  Just curious.

>Gee, Lary, I dunno what your problem is, but how on earth did you get a
>bondout chip?  I have some Microchip hardware around here that could live
>again if I had their special gold plated chips.  I knew I was in trouble
>when I called support and they said 'No sweat.  We'll send you another.  No
>need to return the dead one.  Have a nice day.'

Sounds like you contacted the counter-universe.  Life just doesn't go that
smoothly in this one. <g>

MikeS
<KILLspammikesmith_ozKILLspamspamrelaymail.net>

1997\08\04@190025 by Jacques Bellefleur

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At 10:09 PM 31/07/97 -0400, you wrote:
>I have the ADCON 1 set to 04 hex and the TRIS A register configured to give
>bits 4 and 5 as outputs. When I write port a with a BSF instruction I can
>toggle bit 5 but not bit 4. The Simulator shows it working ok but not the
>emulator. Anyone have any ideas? I already changed the Bondout chip
>thinking I had a blown port. As usual these problems happen on deadline and
>tend to be show stoppers.
>
>As always any help or words of wisdom are greatly appreciated.
>
>
>Larry G. Nelson Sr.
>RemoveMEL.NelsonTakeThisOuTspamieee.org
>http://www.ultranet.com/~nr
>

Set your A Port as binary, by default it is set as A/D input.

1997\08\05@130655 by Larry G. Nelson Sr.

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At 09:56 AM 8/4/97 -0400, you wrote:
>At 10:09 PM 31/07/97 -0400, you wrote:
>>I have the ADCON 1 set to 04 hex and the TRIS A register configured to give
>>bits 4 and 5 as outputs. When I write port a with a BSF instruction I can
>>toggle bit 5 but not bit 4. The Simulator shows it working ok but not the
>>emulator. Anyone have any ideas? I already changed the Bondout chip
>>thinking I had a blown port. As usual these problems happen on deadline and
>>tend to be show stoppers.
>>
>>As always any help or words of wisdom are greatly appreciated.
>>
>>
>>Larry G. Nelson Sr.
>>spamBeGoneL.NelsonspamBeGonespamieee.org
>>http://www.ultranet.com/~nr
>>
>
>Set your A Port as binary, by default it is set as A/D input.
>
>

This wasn't the problem. I am mixing Analog and digital I/O on this port.
The problem ended up being the one Open Drain line on the port. I neglected
the pull up resistor. After adding it the last problem went away.
Thanks to all that helped remind me of that wonderful pin.

;)

Larry G. Nelson Sr.
TakeThisOuTL.NelsonEraseMEspamspam_OUTieee.org
http://www.ultranet.com/~nr

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