<div><font face="Arial, Helvetica, sans-serif">Francesco,</font> <font face="Arial, Helvetica, sans-serif"><br>
<br>
Just on a long shot, have you tried a different display matrix chip? There seems to be some sort of latency in the column. The puzzling part is that you are getting a wrap around from what looks like a "9" display from column 4 back to column 0 in your video. Everything else seems to follow the adjacent column so the most likely fault, to me, would be a "leak in the last row of THAT specific chip. I'd say timing but it doesn't seem to be happening on any other row and I would expect to see random dots if it were a simple timing problem. The only other possibility I can see might be that the line from the PIC controlling that row is picking up some stray capacitance and not dropping to a low state fast enough. That would be odd since all the others seem OK. <br>
I was recently burned by an IDE Cable with a short and I blamed everything else before I swapped the cable. I could have saved myself a lot of trouble by trying the simple solution first. (I'm not saying I de-soldered everything and started over, but I also won;t say something SIMILAR didn't happen before I discovered the real problem. Sometimes, surplus is surplus for a reason!)<br>
<br>
Good Luck<br>
Steve<br>
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-----Original Message-----<br>
From: Francesco De Comité <Francesco.De-Comite@univ-lille1.fr><br>
To: dprglist@dprg.org<br>
Sent: Mon, 14 Apr 2008 3:20 pm<br>
Subject: [DPRG] Dot matix programming problem<br>
<br>
<div id="AOLMsgPart_0_be031c1e-7ba2-4c6c-a7d5-a592ab3795b9" style="margin: 0px; font-family: Tahoma,Verdana,Arial,Sans-Serif; font-size: 12px; color: rgb(0, 0, 0); background-color: rgb(255, 255, 255);">
Hi, I am looking for some help on a little problem I encounter, while
trying to program a dot matrix circuit (namely KingBright TA21-11EWA),
using microchip's PIC18F4620. <br>
The last dot of a column, if near from a lit pixel, also seems lit.
What's could be the reason of that ? Any idea ? <br>
Wiring detail : <a __removedlink__1670794462__href="http://www.flickr.com/photos/fdecomite/2413690327/" target="_blank">http://www.flickr.com/photos/fdecomite/2413690327/</a> <br>
<br>
Little video illustrating the problem :
<a __removedlink__1670794462__href="http://www.flickr.com/photos/fdecomite/2414510950/" target="_blank">http://www.flickr.com/photos/fdecomite/2414510950/</a> <br>
<br>
Source code : <a __removedlink__1670794462__href="http://users.tvcablenet.be/personal/tvcn28401/dotmatrix.c" target="_blank">http://users.tvcablenet.be/personal/tvcn28401/dotmatrix.c</a> <br>
<br>
Thanks in advance for your help ! <br>
<br>
Francesco De Comité <br>
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