See ESP8266 remote power display for energy monitor – EV3 for an update…
ESP8266 remote power display for energy monitor documented a design and some variations for a real power display display using emontx3 / emonhub / mqtt. This article documents a simple compact implementation.
The remote power display uses a ESP8266-12E devkit 1.0 module, a common 3.3V 4 digit 14.2mm seven segment LED module with 74HC595 shift register per digit. The particular LED module has sufficient space to mount the ESP8266 inside the module.
Above, the interior of the module that suits the implementation.
It seems impossible to buy the ESP8266-12E devkit 1.0 module without header pins, so they will need to be removed to allow the module to mount snuggly against the rear cover of the LED module. That done, a couple of holes in the rear cover, and some cutouts in the LED module cover and side for access the USB socket and the ESP8266 can be fixed to the rear cover with some M2.5 nylon screws.Above, a cable for the display is cut and soldered direct to the ESP8266 module (do this with the module separate from the cover, and select the cable end that will not require a 180° twist).
Pin mapping for nodevars.lua to suit this cable connection is RCK=6, SER=8, SRCLK=7, and set invert_display=true.
The code is written in Lua script. It is under active development, the code as it evolves is available online https://github.com/owenduffy/rpdiotm.