Subject: RE: [Elmer 160] PIC El Programming Problems
From: Craig Johnson (cbjohns@cbjohns.com)
Date: Sat Feb 28 2004 - 00:27:35 EST
Kevin, >> Please tell me more about this. I assume you mean that you >> see CTS swinging from >> +4v (nominal "high") to -4v (nominal "low"). Something like >> that, right? >No, it is only swinging from +4 to +0.4V Then this is at least one of your problems. When TD is asserted, it should have -12v (nominal) on it. This should pull CTS below zero for the lows. What do you get on TD when it is "asserted"? (I think you said once, but I want to make sure, and I can't find it in the archive.) Assuming that it is -12v or so, I wonder about diode D4 or R7 or R8. > It reads the program I am able to install with the PICALL. This is really confusing. It indicates CTS is going low enough after all. >> Do you have a solid 5v (or close) coming out of the U2 >> voltage regulator? Again, I would like to know what "high" >> and "low" voltage levels you see at >> RB6 and RB7 when you are trying to Write to the PIC. >Yes, 5V on the money. >My problem appears to be RB7. It is only getting to 1.2V, which is a low. >RB6 is getting up to 1.6V. What could cause this? Neither of these are very good highs. Here's something to try. Try REMOVING the LCD from the socket while you try to program it. The PIC pins RB6 and RB7 are also connected to the LCD, so maybe there is an interaction. Looks like we will have to take this off line now, Kevin. We'll find it. -Craig, AA0ZZ
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