OpenSprinkler for Sonoff 4CH Firmware

This is the unified OpenSprinkler firmware adapted to runs on Sonoff 4ch, without a display and expansion boards.

TODO: Prepare a PR with all modification to be added to the original OpenSklinkler-Firmware repo.

Building the firmware

Hacking the Sonoff 4ch

For this setup, if you want to use a regular Sonoff 4Ch (Rev1/Rev2)is needed to split the load in (AC) and Relays, because the most irrigation valves are AC 24v poweded. If you want to use a Sonoff 4ch Pro, skip this step.

Disconect any power or connection
Open the Sonoff putting off the 4 screws on the back
Using a soldering iron, remove contacts (solder) between the resistor and the first relay. In the next images the zones are yellow colored.

Check with a multimeter the non continuity between both points.

Mappings

Internals:

Blue LED or WiFi LED show WiFi connectivity status: ON=WiFi Connected / SlowBlink=Connecting / FastBlink=Initializing
Stations 1 to 4 are mapped to Relays 1 to 4.
Statios 5 to 8 are soft stations, you can use with a HTTP, like another sonoff basic or pow with Sonoff-Tasmota firmware for example.

Externals:

102 --> Flow Sensor --> GPIO02
VCC3.3 --> Positive 3.3v
RX --> External Relay --> GPIO03 Serial TXD
TX --> Rain Sensor --> GPIO01 Serial RXD
GND --> Negative

Preparing Sonoff to upload

Disconect power from Sonoff
Hold button 1 and connect serial adaptor
Release the button after 5 secs
Check that all LEDs are OFF

Ardunino IDE

First, configure the IDE:

Add this URL to the Board Manager : http://arduino.esp8266.com/stable/package_esp8266com_index.json
Additional info https://github.com/esp8266/Arduino
Install the ESP8266 version 2.4.1 with the Arduino IDE Board Manager Menu
Configure board options as follows:

Second, Donwload and updload the code:

Download the code in .zip
Extract zip file
Open OpenSprinkler-Sonoff4ch/OpenSprinkler-Sonoff4ch.ino
In Arduino IDE, go to Upload

Linux (command-line)

First, download code needed:

$ mkdir ~/workspace
$ cd ~/workspace
$ git glone https://github.com/bibarrav/OpenSprinkler-Sonoff4ch
$ git clone https://github.com/esp8266/Arduino.git esp8266_2.4
$ cd esp8266_2.4
$ git checkout tags/2.4.1
$ cd tools
$ python get.py

Second, make some change to ESP Core code:

Go to ~/esp8266_2.4/cores/esp8266
Open file Updater.h, and locate line 144 that says private:
Right above that line, add a function as follows:

void reset() { _reset(); }
basically it wraps the private _reset() function into a public reset() function.

Third, compile the firmware:

$ cd ~/workspace/OpenSprinkler-Sonoff4ch
$ make -f make.lin30

Finally, upload the created firmware to the Sonoff.

Enjoy!