Re: Homebrew STG card

[stratton-at-mdc.net]

> I've been giving some thought to a 'low cost' STG type board - I don't know if
> anyone on this list has any comments ?
> At the moment my thoughts revolve around a minimum chip count using a half
> length AT card. Basic spec at the moment consists of the following :
> 24 digital IO - 8255 chip
> 4 to 8 quadrature inputs - LS7266R1 ( 2 encoders per chip)
> 8 buffered analog outputs - 2 TL084 and a MAX547 DAC
> Plus 3 or 4 74ALS buffer and glue logic.
> Would there be anyone interested in writing a suitable emc module ?
> 

I think the card sounds like a good project (ie, it was on my own
long-term to-do list).  I'd make two suggestions:

1) Study the EMC driver for the STG board and any other documentation
and then build something that is as close to being software compatible
with it as possible.  Then maybe your board could be just another
option (like STG 1 or 2) in the current module.

2) Protoype a single channel implementation of just the DAC (and maybe
encoder if you don't already have a board for that) and acutally run a
motor with it.  This is the kind of system that looks extremely
straightforward on the digital side, but who knows what gremlins will
pop up in the analog portion.  With luck, your first PCB order will
then be useable.

Chris

PS - with ISA slots dissapearing from commodity PC's and PCI a pain to
deal with, I start to wonder about something that would hang off an
enhanced parallel port interface.  Software of course gets more
complicated then.

-- 
Christopher C. Stratton, stratton-at-mdc.net
Instrument Maker, Horn Player & Engineer
30 Griswold Street, Cambridge, MA 02138
http://www.mdc.net/~stratton
(617) 492-3358 home/shop