Looking for ST-4 protocol

[snowyskiesau]

I've spent the last half hour or so looking for details of the ST-4 autoguiding protocol with no success.

All I've found so far is the pinout for the connector i.e.
· (1) Open or sometimes powered
· (2) Common (ground)
· (3) RA+
· (4) Dec+
· (5) Dec-
· (6) RA-

No mention of voltage levels, pulse width etc.

I'm playing around with microcontrollers and seeing what I can produce in the way of a stepper motor driver for a simple mount (perhaps a Haig/Scotch mount?)
While the basic setup should be easy enough to do, for some reason, it seemed like a good idea to allow for some sort of autoguiding. The late hour may have something to do with that

[AndrewJ]

Gday Jeff

There are no "protocols" per se.
St-4 ports operate by having weak pullups on the 4 "guider" lines,
( inside the scope controller ), that operate in On/OFF mode.
Whatever is "doing" the guiding normally just has relays or transistor switches inside it that connect the lines to ground.
When the "guider" line is shorted to ground, ( by the guider switches ),
the system should start guiding on that direction.
What voltages are used doesnt really matter as long as both ends can handle them, but most operate at 5V.


Andrew

[snowyskiesau]

Andrew,
Thanks for this.
I found a few references to an ST-4 'protocol' which made me think the interface may be more than a simple on/off system.