Irrigation-with-display

Garden irrigation based on Sonoff 4ch, with built-in Nextion display

Getting Started

Architecture

Using Sonoff 4ch Pro to control four 24V AC valves (Gardena). The control of the solenoid valves is simple - open the valve by connecting 24V to it, it will close automatically when disconnected. I am using the original Gardena 24V AC adapter - one of its wires wire is connected to the (1-4) Sonoff 4ch Pro C (common) connectors. The NO (Normally Open) connectors (1-4) are then connected to the solenoids. The second AC adapter wire is then connected to the second contact of all 4 solenoids.

The Sonoff relays (galvanically separated from the main device power supply) then control open valves by closing the relay. The irrigation logic uses the ESPHome native sprinkler controller. For more details, check the ESPHome documentation.

Additionaly, there is a ITEAD Nextion display showing the remaining time. It also has 2 buttons to start automation scrips from the touch screen. The display is connected via 4 wires: GND, +5V, RX, and TX. So to control the display is extremely easy - just connect these 4 wires to the corresponding ports in the Sonoff 4CH. GND, TX and RX is easy. But you need to find the 5V contact. This can be done in 2 ways - either power the whole Sonoff 4ch Pro by 5V (which is what I have done). Or power it by mains and find a 5V contact on the circuit board.

Design

I used Nextion Editor to create a layout for the display screen. There is a static image background with all graphics that do not change (including text, icons, frames, or color background). On top of the background, I created text objects for all the values that change. When the design is finished, you can upload the layout to the display from the NextionEditor using the serial connection (via USB FTDI board).

The program is then very simple - it just sets the text value for the individual text objects. For example, for the inside temperature it does this:

it.set_component_text_printf("irrigation.time1","%02d:%02d",remaining_time/60,remaining_time%60);

ESPHome can read Home Assistant sensors through API, so the ESPHome sensor "rain_today" is linked to Home Assistant sensor sensor.rain_today this way:

sensor:
  - platform: homeassistant
    id: rain_today
    entity_id: sensor.rain_today

It is using the 2.4 inch Nextion display.

Source files

irrigation.yaml - this is the main file - the actual ESPHome configuration
irrigation-advanced.yaml - another version of the file with more options - it publishes the times to the Home Assistant API, so they can be changed from HA. It also uses the following file with 3 functions that make the script much easier overall, so you need to save the irrigation.h file to teh esphome directory together with this file.
irrigation.h - 3 custom functions used in the advanced example (they do the same thing as the main file, just simpler)
display.HMI - this is the actual design of the display I use - the file can be edited via the NextionEditor (can be downloaded from ITEAD pages)
images (folder) - I have included the source images for the Nextion display editor. These are not essential for the project, but if you want to create own design, you can start from there.

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