Hi Andrew,
I haven't used the linistepper, but I've used other stepper controllers and have developed a picaxe based interpreter that parses ascom serial commands to routines.
A microcontroller would be needed as the interface between the stepper controller and the PC. so you can use any stepper controller. I can't see any other way of doing it.
if you look at ascom commands for focusers, there are only a few and its quite easy to write a routine that looks for certain strings in the serial data and when it sees that, it jumps to a sub routine and executes.
just as an example, if it receives the ascom equivalent of move forward, back, rate, etc, it can be programmed to set direction bit, microstepping rate and send pulses at a predetermined rate.
with this you could make it go forward, backward, hi speed, lo speed etc.
I like the DRV8824 based controller as it has 1/32 microstepping.
you can also use the Allegro stepper controller, it has 1/16 microstepping and is very easy. it can drive 1.2A.
http://www.robotgear.com.au/Product....Driver-Carrier
I've been meaning to develop a similar one based on RF as then you just need a small box with the mcu, battery near the focuser and the transmitter could be near your PC.
Cheers
Alistair
