Countdown timer for a Sonoff switch or a random relay, written in MicroPython.

• Simple countdown timer
• Relay is off when the device is powered. Press the button to add 30 seconds, or a different customizable time increment
• Hold the button to turn it off
• Connect it to Wi-Fi to control it using a simple web UI

Edit the variables at the beginning of the script to customize.

Then, in your boot.py add the following code to run it:

import timer
timer.main()

DO NOT EXPOSE IT TO THE PUBLIC INTERNET!

The web server is extremely basic and intended to be used in private networks only!

Uasyncio is included in MicroPython builds only for ESP8266/ESP32 boards with 1MB or more flash.

For ESP8266 boards with 512KB of flash such as the Sonoff Basic, you need to rebuild MicroPython yourself, or you can use my build here (MicroPython v1.13): esp8266-512KB-uasyncio.bin

I created a patch that disables a few unused drivers, TLS supports (it's not very good anyway) and the WebREPL to reclaim some space, and adds the uasyncio module. You can use rshell as a replacement for the WebREPL to edit the files.

Building it is just a matter of running the following steps on GNU/Linux (requires docker, git and esptool).

You can copy the script into the ports/esp8266/modules directory to pre-freeze it and include it in the firmware, but you need to reflash it every time you want to perform any changes.

git clone https://github.com/micropython/micropython.git --recursive
git clone https://github.com/micropython/micropython-lib.git --recursive
git clone https://github.com/Depau/upython-relay-timer.git
cd micropython
git am < ../upython-relay-timer/0001-Slim-ESP8266-with-uasyncio-built-in.patch
alias esp='docker run --rm -v $HOME:$HOME -u $(id -u) -w $(pwd) larsks/esp-open-sdk'
esp make -j12 -C ports/esp8266 BOARD=GENERIC_SLIM

If you built it yourself the firmware will be located at ports/esp8266/build-GENERIC_SLIM/firmware-combined.bin, otherwise you can use my build.

Follow the official MicroPython instructions.

Here is also a guide to flash a Sonoff by soldering the UART header, the header might be in a slightly different location but otherwise it's the same.

esptool.py --port /dev/ttyUSBx erase_flash
esptool.py --port /dev/ttyUSBx --baud 460800 write_flash --flash_size=detect 0 ports/esp8266/build-GENERIC_SLIM/firmware-combined.bin

If you are using an ESP8266 with 1MB or more of flash, there's no need to create a custom build. If you're using an ESP32 with 512KB, you're on your own, read my patch and perform the same things on the ESP32 port.

In short you can copy the 1MB build configurations, make it use the 512KB linker script and remove unnecessary modules such as NeoPixel driver, WebREPL, ussl (basic TLS implementation), etc.

GNU Affero General Public License 3.0