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A LED matrix clock, and cat flap monitoring, with ESPHome

Posted <2023-01-09 Mon 18:56> by Aaron S. Jackson.

I don't know why, but I quite like LED dot-matrix displays. Big chunky LEDs, easy to read even without my glasses, low powered, capable of both graphics, letters and numbers… what's not to like? So I bought some MAX7219 based LED matrix panels. They are 8x8 pixels each and I put them in a long row, so the total resolution ends up being 64x8.

In addition to showing the time, it also shows me IRC mentions and emails. The IRC mentions are using a short nodejs script which connects to IRCCloud and forwards mentions to MQTT. Email notifications are emitted (also via MQTT) by a script called by Dovecot sieve. I managed a few days before I ended up making a case for the clock. At first, I tried making one out of wood, which was going ok until a cut a piece too short. So then I quickly made on one the laser cutter instead. The MQTT topics are subscribed to in Home Assistant, which calls a service running on the clock's microcontroller using ESPHome. Some pics…

Also on the topic of ESPHome, tonight I played with an RFID animal tag sensor. I sellotaped this to my catflap and now I can see the last time each cat used the flap :-) I need to find a more permanent solution to mounting this to the catflap, but it's ok for some experimentation.

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