The objective of the learning scenario is to set up an automatic irrigation system for a greenhouse / flower pots.
Different learning contents are considered:
- Use of sensors: 1) humidity and temperature 2) humidity and water level
- Use of an external display / as an extension Input of threshold values for humidity / water level
- Coupling of different circuits (pump, sensors)
| Creator | Jan Pawlowski, Martin Idzik |
| Subject | Biology, computer science |
| Length | 45 minutes |
| Pedagogical Approach | Explorative learning |
| Competences | New technologies |
| Grades | Primary school, grade 5-6 |
| Technologies | The following components are required Arduino Uno board, plug-in board, resistors, LEDs, connection cable, USB cable The Arduino should already be prepared, the PCs must each have the Arduino IDE (https://www.arduino.cc/en/Main/Software) and the Open Roberta Connector extension (installation for Windows 10: https://github.com/OpenRoberta/openroberta-connector/releases/download/v1.2.1/OpenRobertaConnectorSetupDE-v1.2.1.msi). The software environment can be found at https://lab.open-roberta.de A summary of the preparation here: https://jira.iais.fraunhofer.de/wiki/display/ORInfo/Vorbereitung+Nepo4Arduino Additionally needed: – Temperature sensor (DHT11 or TMP36) – Humidity sensor (DHT11) – Water level sensor – Water tank, hose, cable tie – MOSFET transistor Optional: Display (preferably I2C 16*2) / Touchscreen |
1. Contextualization
The students are each given a dried out flower pot. Alternatively, situations from biology lessons can be used (“how much moisture does a certain type of plant need, e.g. garden cress”).
2. Exploration
The students explore the use of sensors. First, the moisture sensor and water level sensor are connected. Different states of the earth are tried out (completely dry, completely wet). They consider how to construct an irrigation system.
Then the pupils think about what plants need – variables and rules / conditions are formulated that are needed to control a greenhouse.
To do this, use Greenhouse (Preparation) Worksheet and Greenhouse Step-by-Step Worksheet.
Document link: https://docs.google.com/document/d/1ecf7-Kwcs1BpJlKbNfM6AbCzbvCvL39Ffc9elMY8cls/edit
Document link: https://docs.google.com/document/d/1ZiEFRpyniykquGGBfsUJZFhrQVYWKz0BtAl4BmbFwqk/edit
3. Elaboration
1. Connect first sensors
The elaboration starts with the assembly of the Arduino with the two sensors. The sensors are connected to analog pins. First, it is tested which values the sensors deliver in dryness or without water. Then the sensors are tested further (damp earth, water tank filled a little).
As an extension, 2 LEDs can be connected which light up when a certain value is exceeded / undershot.
2. Connect additional sensors
Now more sensors are added, such as temperature, humidity or brightness sensor
As an extension, 2 LEDs can be connected which light up when a certain value is exceeded / undershot.
3. Use display / touchscreen
First, the values are output on the serial monitor (PC). Then an additional external display is connected, so that the computer does not always have to stand at the flowerpot.
4. Connect pump
The elaboration starts with the MOSFET transistor. It can be discussed how different circuits are coupled together, since the Arduino is overloaded at current >40mA or only provides a power supply of 3.3V or 5V.
Then a circuit is designed that switches on a pump as soon as the humidity falls below a certain value. In addition, it is to be tested whether there is water in the tank, since the pump must not run dry.
The system is installed in a greenhouse / flower pot.
4. Reflection
How else could the system be expanded?
