Ok, TBH I don’t really have nice pictures of the hardware.
Nevertheless i want to tell you about my automation -
Battery/Solar powered soil moisture sensor
Currently i have a raised bed that is being watered automatically depending on the current weather forecast in combination with the soil humidity.
Weather forecast is nothing fance - just Weatherunderground binding.
The “fancier stuff” is the sensor that is constantly measuring the soil moisture.
Hardware for the sensor:
- Arduino mini (3.3V)
- Capacitive soil moisture sensor (ordered by Ali)
- 5V/500mA Solar panel
- 18650 Battery
- Battery charging circuit to avoid over/undercharging
- 433MHz transmitter
- 3D Printed case
Since I do not want to run into too much battery drain, i’ve decided to remove the power LED and the voltage regulator from the arduino, as described e.g. here: http://www.home-automation-community.com/arduino-low-power-how-to-run-atmega328p-for-a-year-on-coin-cell-battery/
In order to have a constant power supply, i’ve decided to use a 18650NiMh Battery that is being charged via an additional IC that managed the charging current and also has an output where I directly can connect my Arduino.
Most of the time, the arduino is in deep sleep. It wakes up once in a minute, and transmits the sensor readings + battery voltage vie 433MHz
Hardware for the receiver:
- An ESP32 (maybe a bit overkill)
- 433MHz SuperHET receiver
The ESP reads the data from 433MHz and sends them to a MQTT broker.
Openhab checks the soil moisture and depending on some states (uper/lower limit, time of day, season, weather forecast) it will open a Valve that is watering the raised bed.
To avoid turning your garden into a swamp, a few things have to taken care of:
- Switch off the valves immediately when the sensor or ESP32 goes offline
- Switch off the valves after a maximum time
- switch off the valves when a certain moisture level has been reached
This is maintained by a bunch of rules - of course to be more save it also would require to measure the water flow and have a second valve to close if the first one fails for some reason.
The result of all is logged into influx and I have a chart for displaying it:
Sorry for not having pictures yet. If you want i can post some later. I’m taking the sensor inside during winter