As Ethan pointed out, the trickiest part about DMX512 w/ a UART is getting the extended break length right for the cycle restart and matching the 250 kbit/s rate. Beyond that, the transport layer matches EIA-232/485. And DMX512 isn't so non-vintage computing related. I did some faux lighting panels for a Thinking Machines CM-2 recently. The controller is built around an ESP32 with BT/Wifi. I thought about adding support for artnet so the 4096 individually dim-able LEDs can be controlled with standard DMX universes :) Have to finish the project in January. Would be a good way for non-technical museum people to setup lighting patterns. -Alan On 2018-11-30 16:46, Ethan O'Toole via vcf-midatlantic wrote:
Trying to get a lighting controller to talk to 1986 vintage microprocessor based lighting control packs.
This is my world!
The PHY layer of DMX-512 (lighting control protocol) is RS-485.
Yes. Given that it's 1986, are you 100% sure it's DMX-512? If so you are good.
Anyone have code samples that could be used as a starting point, or should I break down & buy the USB to DMX-512 cable?
You can get a cheap ($7) FTDI based USB to RS485 dongle from amazon or eBay. The FTDI chip can't natively do the proper break space but they have a trick of resetting the chip to get the proper spacing for the restart of next set of 512 channels transmitted.
With this adapter (which is similar to the $50 EnTec OpenDMX) you can use free software in windows like FreeStylerDMX or QLC+, or if you wish to go the linux route there is the Linux OLA package which can do Artnet and 1.31 sACN in and translate over to physical DMX512 (via RS485 dongle.) OLA has a web interface that lets you tickle the channels with a web fader board, and could easily be scripted.
At the laser enthusiasts gathering I go to I've done a presentation or two on running OLA on a PI to do cheap Artnet/1.31 in over to DMX512. I can dig up the slides.
Actually, since the presentation is on the evil cloud I just opened up access and here is the steps to install the OLA bits on debian/pi: https://docs.google.com/presentation/d/1MqJrwKCAL_tw4t-VnQWevSvXTlszwFy-clEC...
- Ethan O'Toole