Re: Homebrew STG card

["Matt Shaver" <mshaver-at-erols.com>]

> From: Paul Corner <Paul.Corner-at-tesco.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'm right there with you as far as my desire for such a card. I'd like to add
two 8254 ICs to provide high frequency stepper outputs as well. I think the
STG driver could be modified to support a card like this since the quad
decoders and the DAC are the same. We can leave out the interrupt control
stuff as it's not used by the EMC. The MAX547 has a clear input that we could
tie into a watchdog circuit to zero the DACs in case of a timeout. I'd also
like to have the outputs on a 100 pin high density SCSI connector* on the
card edge (stock molded cables are available for this). Do you think it would
be useful to include analog input? I think we should have the board
professionally laid out and I might be able to pay for a prototype.

Matt

*See:
http://www.web-tronics.com/100pinscsisc.html ($149 includes the cable below)
http://www.web-tronics.com/100pinhigden.html