> I will write a control program for my telescope. There a three
> stepper motors. No hardware inputs at the moment. The steppers
> are controlled by a 8255 chip. I must control each bit of the
> two ports independent of the other bits.
>
> With the functions:
> set bit
> reset bit
> flip bit
> flip bit periodic
>
Hi Juergen,
I am also working on a project for controlling a telescope :-) My telescope,
however, uses DC motors and I control their speed by pulsing bits on the
parallel port. But the general problems are the same as yours. I have come
up with the following solution:
I use 2 threads pr. motor - one thread sets the bit, the other resets it.
They are scheduled with the same period, but at different times. The delay
between high and low controls the motor speed. I use a third thread to
control the the other 2 (6 actually - having 3 motors :) setting timing,
starting and stopping them. The idea is that the control thread also reads
commands through a FIFO from a regular mode Linux program and sends
responses. I haven't coded that far yet.
I can send you some source files privately, if you are interested. We should
keep in touch - we'll probably run into similar problems later :-)
Greetings
Henrik
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