It's a good day when a middle-of-the-night idea results the next day in two PCBs designed and sent to JLCPCB for production.
I'm monitoring various temperatures on the boiler heating system in my basement (3 zones), and want to replace my old system using PICAXEs and little routers with an ESP32-S2Mini running Annex. I want to have the ESP in a closet on the first floor, and run CAT5/6 to the basement. I realized that I could use the inner pin rows of the S2Mini by getting 3V3/5V to the rows--that way the S2Mini could have a base-board PCB for the outer rows (matching the ESP8266 D1Mini), and a "hat" for the inner rows.
Here's the EasyEDA design:
On the other end of the CAT5/6, it could use this RJ45 breakout board from Aliex: https://www.aliexpress.com/item/1005007136034321.html
Or you could cut out the middleman with another EasyEDA design:
The Aliex breakout PCB could connect to a 1x to 8x relay module: https://www.aliexpress.com/item/1005006653819752.html (This module works reliably with the 3V3 output pins of the ESP32 when 5V is supplied to DC+, but not with 3V3.)
For the inner-rows hat PCB to connect, long pin headers need to be used on the 5V, 0V, and 3V3 holes, and no pins on the inner top two left and inner bottom two right (assuming 5V pin is upper left).
Gerbers attached
ESP32-S2Mini Inner Pin Hat PCB
ESP32-S2Mini Inner Pin Hat PCB
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