Saturday, November 16, 2019

Two more display modules

Today I finished two more display modules.

One of them uses one of the new XBee 3 wireless modules. It initially didn't work with the XBee 2 that I had, until I realized I needed to install the 802.14 firmware. Once I did that, it was plug-and-play compatible with both hardware and software.

The most crufty part of the build is the tiny resistor network which provides reliable pullup and pulldown voltages for the quadrature encoder knob. I tried using the internal Raspberry Pi GPIO pullups for that purpose, but they don't seem to push enough current to produce reliable results when turning the knob quickly. So resistor network we must have. If I were to make this design in any quantity, I would spin up a PCB for that tiny thing -- but right now the protoboard is adequate. I am not sure the brightness of these displays is where I need it to be anyway, so I hesitate to "standardize" on this design.

Here are some build photos for your enjoyment.

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