Stache on USB Stamp?

Humanoido

The Stache is a tiny indispensable black box (nearly the same size as a 9-volt battery),
capable of holding 15 programs, each or several of which can be selectively loaded
into Basic Stamps. This is a remarkable product!


Stache connects to SERIAL boards. What about USB?

It was brought up, in this thread
http://forums.parallax.com/showthread.php?p=765140
that a Stache is designed for serial use, not USB, when connecting to the Stamp.

The Stache manual confirms its intended use as a serial device. As of this posting
there is no USB version Stache.

As we are a group of thinkers, hackers, experimenters, and designers, the question
of "How to connect the Stache to a USB Stamp Board?" remains.

humanoido

Post Edited (humanoido) : 1/24/2009 5:58:51 AM GMT

marzec309

With a custom cable after the FTDI Chip.

Humanoido

Schematic? Cable details? Project examples or referrals?
Any changes in software necessary? Consider that someone
will do this project and describe how to accomplish this goal.

humanoido

SRLM

I think I mentioned it on the other thread, but you can just bypass the USB part (right?). Since all the FTDI chip does is convert USB to serial, it would be pointless to convert serial to USB and back to serial. Take out the middle man... You'll probably need a small board to put various passives on, and a way to get a reliable connection to appropriate stamp pins, but it shouldn't be that hard.

Tracy Allen

Humanoido, Thanks for the kind works about the Stache. I think SRLM is on track for the easiest method. Like the Pro development boards that have both the USB and serial interfaces, the serial interface bypasses the FTDI chip.

One thing that makes this difficult to do simply by adding an FTDI chip is that the Stache has to emulate a Stamp in both directions. That is, when you connect the Stache to your PC, it is a DCE device and receives the DTR reset pulse and data on its DCE pins. But then when the Stache is in the field, it has to emulate a PC, so it acts as a DTE device and transmits and receives on the opposite pins than it used when it was DCE. That dual function is taken care of by circuitry around the SX microprocessor and uses the fact that the SX pins can be both inputs and outputs. That would take extra crossbar switching to implement with an FTDI chip.

I should add that the FTDI chip would have to act as a USB slave in one direction and as USB master in the other. I think the FTDI or Vinculum chip is capable of that, but it is more involved than acting in the more familiar role of slave alone.

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Tracy Allen
www.emesystems.com

Post Edited (Tracy Allen) : 1/24/2009 8:41:29 PM GMT