This MicroPython project on an ESP32-C3 (SeeedStudio Xiao) uses weather API's to determine if significant rain has fallen in the last day, or is forecast today, and if so disables the garden watering system to conserve water. It reports the rainfall and system status to ThingSpeak.

The project is run off a single 3.3V 1600mAh LiFePO4 battery (18650) and uses the deep sleep mode of the ESP32-C3 to extend the battery life.

This controller is suitable for use with automatic watering systems which expose the ability to disable the system by making a connection open circuit.

The current release of firmware for the ESP32-C3; v1.9.1, does not support deep sleep. I built my own firmware using v4.4.3 of the ESP-IDF and the v1.9.1 tag of the Micropython with patch esp32c3_wakeup_ext.patch (from modmachine: Implemented GPIO wake-up for ESP32-C3) applied.

If the schematic appears to be missing details, download it and view it locally, or zoom the web page.

I used a polycarbonate box with a build-in O-ring seal. A PTFE breathable vent was fitted to allow air, but not water vapor in and out. The electrical connections exiting the container to the watering system must be completely sealed.

All weather API calls and rain calculations are in weather.py, you will need to update the services called and the code used to extract data from the responses.

Configure a ThingSpeak channel something like:

Download the library:

• urtc real time clock (RTC) library.

Create a file called secrets.py and fill in appropriate values:

"""Secret values required to connect to services."""
WIFI_SSID = 'XXXXXX'
WIFI_PASSPHRASE = 'XXXXXX'
THINGSPEAK_API_KEY = 'XXXXXX'

HEADER = {'User-Agent': 'XXXX'}
LOCATION = 'lat=-XX.XXX&lon=YYY.YYY'

By default the RTC will wake the ESP32-C3 from deep sleep at 5am GMT every day, if you want a different time edit the value of the RTC_ALARM constant in config.py.

Copy all the python files to the ESP32-C3.

Set the 'No Sleep' DIP switch to 'on', press the RST button to reset the ESP32-C3, then connect using Putty or similar serial client and initialize the RTC by executing the following:

import wifi
import clock

wifi.connect()
clock.initialize_rtc_from_ntp()

# Get date time, to verify setting.
clock.timestamp()

Set the 'No Sleep' DIP switch to 'off', press the RST button to reset the ESP32-C3 and connect to your water system.

Connect using Putty or similar serial client:

import water_system as w
w.init_ftp()

Then retrieve the log file using the ip address from above:

curl -v -O "ftp://<ip address>/system.log"