Posted by Pigeon on 1/1/2007, 4:56 am Observing the output of this thing with an oscilloscope and a PIC and comparing the result with this most helpful website leads me to think that although it claims to be a DMX controller, it's actually using some bastardised version which only works with other Geni products. I don't think this is simply due to the appallingly translated manual leading me to operate it wrongly; nor do I think the PIC code is at fault since the output from the PIC corresponds with the oscilloscope display. As I have it, the two sliders on the front panel are associated with the third and fourth frames, the left one with the third frame and the right one with the fourth. As the sliders are advanced, the seven segment display on the front panel advances linearly from 0 to 255. However, the data in the frames does nothing of the sort. For most positions of the slider the data transmitted is a constant 255. For a few positions I observe one of a small number of bit patterns, none of which correspond to the value indicated on the display. Only at zero do display and data correspond. Furthermore, it is not sending a start bit, so when the frame data is 255 there are actually no transitions at all during the frame period, and the frame therefore "disappears" and the PIC receives the next frame instead. When the frame data is zero, the lack of a start bit causes the frame to be "short" and the first stop bit to be read as data, so the bit pattern received is 00000001. Has anyone else had experience of these devices? Are they really not DMX, or have I just got a knackered one?
Link: Pigeon's Nest
213.162.113.17
Someone has asked me to build him a DMX receiver and has given me a Geni DM4 as a transmitter to test it with.
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