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A planned future upgrade is to build a more intelligent camera controller so that you can move to set positions and navigate in a more intuitive way. For now however, this is how its done.
The circuit diagram details exact connections but what we have to control are motors, they take 12VDC to operate, reversing the polarity to move in the opposite direction. After some consideration I decided to use relays to reverse the current flow for simplicity.
One stumbling point was the lens, rather than having two wires for each
motor, one wire from each motor was common. With my driver setup I want to avoid
possible reverse currents or shorts between the 12V and Ground.
From the parallel port the lens has three control lines, these are TTL level signals.
This uses just 3 IO lines and 3 lines of the driver chip but still two relays.
The Pan Tilt mount had two wires for each motor so they were treated separately, using 4 data lines out of the parallel port.
Whilst this uses 4 lines and 2 relays with does allow us to easily pan and tilt simultaneously.
The parallel port is fed by the website Perl backend, giving bit wise control of the port, turning the respective bits on to achieve the desired effect.
If you would like a look at the code or anymore specific information to set up your own camera then please E-Mail me.