Now that we have a nice enclosure, time to put everything inside.
This time I used a Arduino Uno. For the display, I opted for the well known 32 by 8 dot matrix display, with MAX7219 drivers. At the back, a DHT22 humidity and temperature sensor will be placed and the 433 MHz receiver module. To round it of, an infrared receiver will be placed at the front for the remote control.
The front and back are made from, smoked, plexiglass (to hide the innards). Having a CNC machine makes it easy to have plates that fits precisely. But again, this is something that can be done with a bit of elbow grease and patience.
The display can show the following information:
- Amount of rainwater left in the tank (in liters).
- Amount of rainwater left in the tank (in centimeters).
- Temperature in the storage tank.
- Temperature as measured at the back of the display unit.
- Humidity as measured at the back of the display unit.
- Version number.
- Empty display (useful when you want a dark room, e.g. when watching a movie).
To select the wanted information, I programmed the up/down keys of the small remote control to easily switch between the views. As an extra, pressing the
- button clears all information and everything is set to 0. When the next burst of information is received from the storage tank, the display gets updated again. Very useful to check if the sender is still working (after all, a rainwater storage tank is not a very friendly environment for electronics).