I wanted to write some software to output DMX512 (a lighting protocol) to an RS485 PC card but have problems because of the protocol. It requires 1) a constant data stream and 2) quite precise timings. I cannot get the timing resolution required in software because the PC clock heartbeat is too slow.
How do people build serial controllers with precise timing and automatic data streaming? Are these something that could be controlled on a PC in software?
TIA
Luke
an
slow.
A PC running an operating system like Windows does not make a good real-time platform. If you have to use Windows the answer might be to use a single chip micro hanging off a port to do the real time stuff. eg have the PC send the data to the micro at it's leisure - then have the micro send it out with the accurate timings needed.
Do you mean a single board computer with, say an 68000 processor? Would I then need to write the program in basic and upload it? The only embedded programming I have done was at university but it was not real-time and so I'm not sure how to program the timing required of the port.
Thanks Luke
they use a UART with an apropriate clock rate...
Bye. Jasen
On further investigation it looks like this has all been done before.....
Here is some software for the PC...
it says it works with various DMX512 "Dongles" that hang off the printer port. Google found
A working software.
Another software I can recommend is DMXControl from
I have built this and used that. This works well with DMXControl.
More links to DMX-512 circuits and software can be found here:
-- Tomi Engdahl (http://www.iki.fi/then/) Take a look at my electronics web links and documents at http://www.epanorama.net/
Personally, I'd use a PIC, Atmel being my favorite, to manage this rather simple protocol.
The administration software would be implemented in a PC. Interface this to your favorite USB or RS232 protocol. Have the PIC encapsulated and manage the DMX512 data stream.
Wayne
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