esphome-config-sprinkler

Overview

ESPHome-based irrigation controller for two zones, single pump and up to 6 valves

The controller is capable of working without persistent connection with Home Assistant. That is, Home Assistant is only used as the UI (and possibly automations) but does not perform actual operations including scheduling and valve management.

Motivation

Looking for alternatives to replace old K-Rain offline controller author found 8 relay controller for Raspberry Pi Pico and decided to use it for the new controller.

In fact, there are multiple irrigation controller implementations for ESPHome and Home Assistant - the implementation is intended to be simple enough and introduce no new UI controlling it, as well as requiring no persistent connectivity with Home Assistant. The Home Assistant instance could even be coming online only when changes to controller configuration are needed.

Controller configuration

• Two zone groups
  • Lawn with 3 zones
  • Flowerbed with 2 zones
• Single pump with water tank
• Valve on the inlet pipe to refill the tank

Optionally you could add LCD display to see controller status and RTC to provide accurate clock.

Home Assistant entities

Following Home Assistant entities are exposed by the controller:

Software

• ESPHome
• Sprinkler component is the key to the functionality
• Dynamic 'on-time' component is to allow changing schedules without recompiling the firmware (as with on_time trigger for time components)

Hardware

NOTE 1 Author is not affiliated with the hardware vendors below, that is what I used to build the controller.

NOTE 2 There are no strict requirements to use Raspberry Pi Pico - ESP8266/ESP32 would also work given it has sufficient GPIOs via an extender and configuration modifications to change GPIO pins.

• Raspberry Pi Pico W
• Industrial 8-Channel Relay Module for Raspberry Pi Pico (Pico-Relay-B)
• A 5V power supply, Meanwell HDR-15-5 (5V, 2.4A, DIN rail mounted) has been used
• Irrigation (valves, pipe, pump, water tank) - likely very specific to this implementation, though the solution could be adjusted accordingly

Optionally:

• A DS3231 RTC. DS1307 would also work but has lower accuracy and is a 5V unit (most of Raspberry Pi Pico pins are 3.3V)
• A PCD8544 display

GPIO layout

GPIO	Purpose	In stock Pico-Relay-B
GPIO21	Relay 1 (lawn, south zone)	Y
GPIO20	Relay 2 (lawn, north zone)	Y
GPIO19	Relay 3 (lawn, west zone)	Y
GPIO18	Relay 4 (flowerbed, south zone)	Y
GPIO17	Relay 5 (flowerbed, west zone)	Y
GPIO16	Relay 6 (not used)	Y
GPIO15	Relay 7 (water tank refill valve)	Y
GPIO14	Relay 8 (water pump)	Y
GPIO13	RGB LED	Y
GPIO6	Buzzer	Y
GPIO0	Rain sensor	N
GPIO1	Water tank empty sensor	N
GPIO4	Input (not used)	N
GPIO5	Input (not used)	N
GPIO2	PCD8544 CLK	N
GPIO3	PCD8544 MOSI	N
GPIO22	PCD8544 Backlight	N
GPIO7	PCD8544 Reset	N
GPIO10	PCD8544 CS	N
GPIO11	PCD8544 DC	N
GPIO8	RTC SDA	N
GPIO9	RTC SCL	N

Pico-Relay-B hardware modifications

The stock Pico-Relay-B lacks GPIO exposed via a terminal - those are needed to connect rain sensor and water tank empty one, the screw terminal (4 pins) has been added (lower left corner).

Also, the hardware initially had no RTC, DS3231 has been added (top left corner).

Finally, PCD8544 display has been added to show controller state (not shown on the image below).

How to use

Include following fragment to your ESPHome configuration (sprinkler name of the package could be anything), it is recommended to use specific release version (see Releases) to ensure your configuration is stable over the time.

A temperature sensor is a prerequisite to the configuration, its ID should be passed via temperature_sensor_id substitution - it is only used by display component currently.

substitutions:
  temperature_sensor_id: temperature_sensor

sensor:
  - platform: internal_temperature
    id: ${temperature_sensor_id}
    name: "Internal Temperature"
    icon: "mdi:thermometer"
    entity_category: diagnostic
    update_interval: 60s

packages:
  sprinkler: github://hostcc/esphome-config-sprinkler/main.yaml@<release version>

The configuration could further be adjusted using substitutions, see main.yaml for details.

You can also remove certain portions of the configuration marked as Optional in main.yaml if you don't have particular hardware or need to use that functionality.

Sample installation

Wiring diagram

TBD