DMX Shield project only works if I touch and hold a particular Arduino pin.

I have a DMX Shield project. It works but only works when I physically touch Arduino pin No. 2 (next to TX) with my finger. This pin is labelled DE2 on the shield. (DE is used to switch between slave and master with a jumper.)

If I simply insert a long (approx 10in) wire into Pin 2/DE2 then it works. If I insert a short wire (5in) into the pin it does not work.

Can anyone suggest what the problem might be please? And, if possible, a more elegant solution than having a loose wire hanging out.

Technical Details:

The Conceptinetics CTC-DRA-10-R2. This is the non-isolated version of the shield (for testing)

The Ardiono project library is DMXSimple.

I have the shield set up as a DMX Master (jumper to DE label).


Without code, it’s quite difficult to help you! And what did the Pi HUT say when you contacted them about your issue with their board?

Did you make sure to set pin 2 to an output and write it high or low?

This was it!

Originally I set pin2 to output and high as I had read. But nothing worked and I thought I should try setting the pin for RX (pin 3) to output/high instead. Then it started working if I was holding the Arduino board. I did not associate the problem with the fact that I was no longer setting pin2 to output and high - frankly not really understanding what that setting was for.