Or, at least, don’t trust my circuit diagrams! Having carefully assembled the one I presented a couple of days ago, I was surprised to find that it didn’t work. Strange… it was just fine when it was running on the breadboard.

A couple of hours later, I had tested all the connections for continuity and fixed a slightly dodgy pin on my Pi breakout interface (it was a touch short due to my dodgy soldering but is now back in line). Fortunately I decided to read back through the tutorials that helped me set up the design in the first place and discovered that I should have been using GPIO4 for data and not GPIO17. D’oh! The ribbon connecting the Pi to the breadboard obscures the pin labels on the left hand side and, somewhere along the line, I had made a mental transposition.

Fortunately no harm seems to have been done and I’ve even got the whole circuit slotted into a project box, just awaiting final setting in place tomorrow. I’ve corrected the post I made on Friday with an updated circuit diagram (fixing a couple of other glitches too) and information. However, next time I post a circuit diagram, don’t rush to copy it blindly. I’ve got a way to go before I can claim to be an expert in electronics!