On Sat, Feb 04, 2006 at 11:50:09PM -0200, Gerhard Fiedler wrote:
> Byron A Jeff wrote:
> 
> >> I'm not sure I get this yet... What's wrong with using the modem pins of
> >> a serial port? Or is this what you are thinking of using?
> > 
> > Most of the reports that I have read have indicated that the modem pins
> > of a USB to serial converter cannot be controlled with the same
> > precision as a traditional serial port. 
> 
> That's also my understanding. 
> 
> But I thought that this programmer's main use is to bootstrap a "real"
> solution (that is, program a chip for a better programmer or program a
> bootloader), so speed would not matter, and slowly wiggling the modem
> signals is possible. (I'm no programming expert, but the programming specs
> I've seen so far didn't list maximum times, only minimum times.) So the
> only addition to a programmer that uses a traditional serial port would be
> a (maybe configurable) timing control that slows the process down.

Or you could add feedback via one of the input modem control pins.

> This might be easier to implement, more straightforward and possibly safer
> (in terms of the programming success).

I personally think that wiring up a couple of 555s with a transistor and
a couple of discrete parts isn't too terribly difficult to put together.
The only think that I've found difficult so far is the RX feedback. But
for code dumping it really isn't even necessary.

BAJ
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