For spontaneous trips, even in midsummer, Make recently presented an automatic watering machine that ensures even watering of indoor plants when you are absent. The article motivated me to try growing tomatoes again after forgetting about watering regularly. As it should be for a maker, you can still make some improvements when recreating it.
Using the probes and pumps from the article, I first built an automatic irrigation system for three tomatoes. So that these are not only watered in one place, I have one Water distributor designed and printed out three times. The distributor can be attached directly to commercially available hoses (ø 9.6mm).
Then I expanded the program for the Arduino Uno to include dry-run protection and an LCD keypad shield (from € 4.39). The currently measured moisture of one of the three tomatoes can be seen there for 10 seconds at a time before the display switches to the next plant.
There is more on the subject in issue 2/20 of Make.
Connect the display
Only a few connections are required to connect the shield (see picture). The 5 volt supply is tapped below. To the right of this are the analog inputs for connecting the humidity sensors and the digital outputs for controlling the pumps in the upper bar. So that the display corresponds to the position of the plants, I have assigned analog input A1 and digital output 11 to the right plant, A2 / D12 to the middle and A3 / D13 to the left plant. If you want, you can go to the program in
acPosition swap the letters ‘L’, ‘M’, and ‘R’ or replace them with other letters.
Pot R, M or L is accordingly also in the top line of the display. The humidity is then displayed as the difference between the measured humidity and the limit value (in the program in the array
ai16Sollwert as soon as the value reaches 0, the pump is operated for 4 seconds (is activated with
PUMPZEIT set). In the second time, the currently elapsed time since the last pumping process and the time between the last and penultimate pumping process are displayed alternately.