The ESP and camera sit at the top of a 3D-printed housing that fits over the meter. The clever trick comes as each photo’s orientation is determined, and not only is OCR used to read digits but ...
“The rest”, by the way, includes bringing the ESP’s processor up, dumping new firmware into it over the SPI/SDIO lines to convince it to act as an SDIO WiFi adapter, and all the rest of the ...