Action: Motion sensor

Next to the output of the moisture sensor, we also need another sensor that recognizes movement in the room. We use the motion sensor for this.

Usage

• The motion sensor is a passive infrared sensor that detects differences in heat radiation within its detection range.
• It responds to anything that moves and emits heat, including your pets 🦖.

Technical Specifications

• Operating Voltage: 4.5 … 20 V
• Output Voltage: 3.3 V high / 0 V low
• Delay Time: 8 s (± 30%)
• Induction Angle: < 100 degrees cone angle
• Detection Range: approximately 3.0 m

Wiring

The motion sensor has 3 pins:

• Negative terminal (represented by a minus sign on the sensor)
• Positive terminal (represented by a plus sign on the sensor)
• Digital Signal (labeled “out” on the sensor)

To connect the pins to your microcontroller, follow these steps:

• Make sure your microcontroller is disconnected from the USB power source before making changes to the circuit
• Connect a cable between the negative pin of the sensor and the G (Ground) pin on the microcontroller.
• Connect a cable between the positive pin of the sensor and the VV pin on the microcontroller.
• Connect a cable between the digital signal pin of the sensor and the D1 pin on the microcontroller.

Programming

Note: If you still have any code in the editor from a previous exercise, feel free to delete it

Here is the corresponding code to display the sensor data in the serial monitor:

void setup()
{
pinMode(D1, INPUT);
  Serial.begin(115200);
}

void loop()
{
bool digitalValue = digitalRead(D1);
Serial.println(digitalValue);
  delay(1000);
}

The values you see in the serial monitor are 0 or 1. The value 0 means no motion detected, and the value 1 means motion detected. You may also notice a delay in the transition from 1 to 0. It takes approximately seven seconds for the sensor to return to 0 after detecting motion.