Q Light Controller+

Hey everyone and merry christmas!

I've tried to get some DMX output via the UART port on a Raspberry Pi 3 Version B.

I'm using the recent download of the complete raspberry image (QLC+ is runnig version 4.11.1) and a simple 75176 / max485 for converting, connected to +5v, GND and the TXD. The circuit is working on a arduino, so this might be right (i've build a few controllers on arduinos). "UART" is ticked on "output" in QLC+.

DMX lights are not working, my swisson dmx tester says "bad dmx" or "error" and the refresh-rate ist 1hz.

Any ideas what might be wrong? Power supply is fine, same problem on a different raspberry....


Best regards
Noel

have you tried reversing the polarity of the DMX signal (swap pins 2 and 3 of the XLR connector)? It may be that the RPi has a different polairy UART output to the Arduino.

I've checked the 75156 data sheet and you should be fine with a 3.3v UART output from the Pi driving a 5v powered driver IC. According to the data sheet the digital input to the driver IC is TTL level, so 2v min for logic 1. The Pi will drive to 3v typically. So it should work!

Doug