----- Original Message ----- 
From: "Byron A Jeff" <byron@cc.gatech.edu>
Subject: Re: Re[2]: [PIC]


> So there are no guarantees that a NoPPP or JDM style programmer will work
> with a USB serial cable.

Actually, I think it is pretty much guaranteed that they won't work.  Well,
NoPPP is a parallel port programmer so of course it won't work <g>

To program a PIC, you need to wiggle three lines and read one.  A PC serial
port has only two control lines, so you need to use TD as one of your
wiggled lines.  The converter will mangle that line since it knows that it
can only carry asynchronous serial data, and it needs to treat it that way
because it needs to shift bit rates between the USB side and the serial
side.  Perhaps you could get real creative and slow down the baud rate and
only raise !MCLR one bit time at a time, but that seems like a stretch.

--McD


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