serial problem - a possible situation

Archiver

Hi all
Back a few days ago i was struggling with my caller id circuit driven
by a BS2OEM. The problem was that the circuit did what it was
supposed to do WITHOUT the serial cable attached (for debugging
purposes). Well i moved the circuit to another computer and BOOM it
worked fine. This morning i remembered that my computer is not
plugged into a grounded outlet (ie - i broke the ground prong (US
120VRMS outlet) so i can plug my computer in - not very safe but the
only solution)
So the only conclusion that i can draw is that THIS must be the cause.
What do you guys think, could this be the problem???
RADU

A short reminder of the situation:
Normal functioning::
-When a valid ring arrives CIDchip drives a pin(R-In) LOW (CID data
sent only if this happens)
-If a valid telco is detected CIDchip drives another pin LOW(C-In)
after which it starts to send the FSK demod data to the STAMP.

Fnctioning with serial cable attached::
-pin R is LOW and stays LOW for ever (no high to low transition when
a ring arrives)
-pin C is HIGH (normal) but does not go low when a valid telco is
detected.
THESE 2 PINS ARE CHECKED DIRECTLY ON THE CID CHIP...not the STAMP! so
the STAMP does not affect these pins

Archiver

Radu,
If you were to use a DVM to measure the difference between pin 5 of the
computer's serial port and the stamp ground before connecting the two, you
should get a very small AC and DC voltage. If either of these measurements
are very far off of zero, then you may have found your problem.
Old joke: "Dr, it hurts when I move my arm this way". Dr's reply: "Don't
move your arm that way!"
Find a way to safely ground your computer!
Mike

At 03:19 PM 3/22/2002 +0000, you wrote:
>Hi all
>Back a few days ago i was struggling with my caller id circuit driven
>by a BS2OEM. The problem was that the circuit did what it was
>supposed to do WITHOUT the serial cable attached (for debugging
>purposes). Well i moved the circuit to another computer and BOOM it
>worked fine. This morning i remembered that my computer is not
>plugged into a grounded outlet (ie - i broke the ground prong (US
>120VRMS outlet) so i can plug my computer in - not very safe but the
>only solution)
>So the only conclusion that i can draw is that THIS must be the cause.
>What do you guys think, could this be the problem???
>RADU
>
>A short reminder of the situation:
>Normal functioning::
>-When a valid ring arrives CIDchip drives a pin(R-In) LOW (CID data
>sent only if this happens)
>-If a valid telco is detected CIDchip drives another pin LOW(C-In)
>after which it starts to send the FSK demod data to the STAMP.
>
>Fnctioning with serial cable attached::
>-pin R is LOW and stays LOW for ever (no high to low transition when
>a ring arrives)
>-pin C is HIGH (normal) but does not go low when a valid telco is
>detected.
>THESE 2 PINS ARE CHECKED DIRECTLY ON THE CID CHIP...not the STAMP! so
>the STAMP does not affect these pins
>
>
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_________________________________
Mike Walsh
walsh@i...


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