Passive Infrared Sensor with micro:bit

Written By: Cherie Tan

Difficulty

Easy

Steps

A passive infrared (PIR) sensor measures infrared light radiating from objects in its view. These sensors collect incident infrared radiation with the use of a Fresnel lens, on a pyroelectric sensor and can detect human movement as long as it is within the range of the sensor. In this guide, learn to connect a PIR motion sensor to the micro:bit. Then learn to program the micro:bit with the PIR motion sensor to display an alert message when such movement is detected. Complete this guide to start incorporating the PIR motion sensor in your micro:bit!

Step 1 Overview of the PIR Motion Sensor

A PIR (passive infrared) sensor also known as an infrared motion sensor is an inexpensive, low-power and durable sensor used for the detection of movement within its range. It includes a pyroelectric sensor and a Fresnel lens. You can see the pyroelectric sensor under the lenses as a round metal can. The curved lenses concentrates infrared radiation toward the sensor. Through a changing voltage level, it detects changes in the infrared radiation level which is why it is commonly used to detect whether a human has moved in or out of its range. There are three pins on the sensor: From left to right as shown: VCC - Voltage common collector DO - Digital output GND - Ground

Step 2 Connect red jumper wire to VCC pin

First, connect a red jumper wire to the VCC pin found on the PIR motion sensor.

Step 3 Connect jumper wire to Digital Output pin

Connect another jumper wire this time to the DO pin found on the PIR motion sensor.

Step 4 Connect black jumper wire to GND pin

Now, connect a black jumper wire to GND on the PIR motion sensor.

Step 5 Connect GND to GND

Connect GND on the PIR motion sensor to GND on the micro:bit

Step 6 Connect 3.3V to VCC Pin

Connect a red jumper from VCC of the PIR Motion Sensor to 3.3V of the micro:bit

Step 7 Connect DO to P0

Connect Digital Output Pin of the PIR sensor to P0 of the micro:bit

Step 8 Code for PIR motion sensor and micro:bit

basic.forever(function () {
    if (pins.digitalReadPin(DigitalPin.P0) == 1) {
        basic.showIcon(IconNames.Happy)
    } else {
        basic.showIcon(IconNames.Angry)
    }
})

Upload the following code into the Javascript panel of the MakeCode editor. To view it in blocks, simply click the Blocks button found on the top of the editor!