Previously I wrote how I designed and implemented a 12 Volt trigger for an NAD D-3020 audio amplifier and on the PCB version to automatically switch the amplifier on and off. In response to those posts I occasionally receive comments asking why I am not using an IR remote control instead of the 12V trigger input. The advantage of IR is that it also allows switching to the corresponding input, and allows to control other devices as well.

A lot of the available IR blasters come with some form of cloud-based integration such as Amazon Alexa, Apple Siri, Google Assistant or Tuya. I am not a big fan of those and prefer to implement my home automation without big tech looking along. Tasmota is a great platform for that; it implements a firmware that can be combined with all sorts of sensors, switches and actuators based on the ESP8266 or ESP32 modules. In the past low-cost IR blasters based on Tuya would have an ESP8266 module and could be flashed with Tasmota, but nowadays many Tuya devices use another non-compatible wifi module.

There are also ready-made ESP8285 IR blaster modules, which are very cheap on Amazon or Aliexpress. I decided to implement my own and learn a bit more along the way. I ordered 6 of these IR LEDs and this HX1838 IR receiver. After an initial design and test on a breadboard, I implemented it as a shield for a Wemos D1 mini.

While translating the initial working design from the protoboard to the perfboard, I initially made the error to use pin D3 for “IRsend” and D8 for “IRrecv”. This would not work for both, seemingly because of their special functions and/or internal pull-up or pull-down resistors of the ESP8266. This page has a lot of details and here is a clear list that orders the best input and the best output pins to use. I switched “IRsend” and “IRrecv” to the neighboring pins D2 and D7, after which it worked fine again.

Note that the old Wemos that I still had lying around is a cheap clone with the micro-USB connector on the opposite side as the ESP12F module. Modern ones have the ESP chip directly mounted on the PCB rather than in the form of an ESP12 module with a metal cap, making the whole design more compact. Due to the way I soldered the stacking pin headers, the pinouts on the board are left-right mirrored compared to what I would consider the normal orientation.

This shows the top and bottom of the IR shield:

The photo below shows the IR blaster mounted underneath the corner of our couch, using a paperclip and some safety pins. The couch is about 3 meter distance from the TV and audio setup.