References:

rtl_433 Efergy E2 Classic decoder:
https://github.com/merbanan/rtl_433/blob/master/src/devices/efergy_e2_classic.c
Original decoder copyright (C) 2015 Robert Högberg.
Original decoder license: GNU GPL version 2 or later.
EfergyDecoder.h implements the documented packet interpretation and retains
that GPL-2.0-or-later attribution.

91JJ Efergy CC1101 ESPHome receiver:
https://github.com/91JJ/Efergy-CT-Clamp-Capture-for-ESP-Home
Reference for CC1101 modem configuration. This is a separate ESP8266 port,
with continuous capture and corrected frequency registers.

ESPHome:
https://esphome.io/components/external_components/

A copy of GNU GPL version 3 is included for distribution under the original
decoder's GPL version 2-or-later terms.
