9. Input Devices¶

Group assignment:¶

Probe an input device(s)’s analog levels and digital signals
Document your work on the group work page and reflect on your individual page what you learned

Individual assignment:¶

Measure something: add a sensor to a microcontroller board that you have designed and read it.

Helpful Documenting of Past Students¶

What Sensor?¶

I decided to use the passive infrared sensor sensor. A passive infrared sensor (PIR sensor) is an electronic sensor that measures infrared (IR) light radiating from objects in its field of view. They are most often used in PIR-based motion detectors. PIR sensors are commonly used in security alarms and automatic lighting applications.

Wokwi¶

Wokwi is a simulater like tinkerCAD. In our lab we are required to first test with a simulator because we don’t want to accidentally to burn out a boards.

This is the code for the PIR sensor in wokwi.

This is the PIR sensor not detecting motion. To simulate the motion I needed to click the button.

This is the PIR sensor detecting motion as you can see. Once the motion was detected the LED turned on.

Code¶

// Define pins
#define PIR_SENSOR_PIN  D3 // GPIO pin connected to PIR sensor output
#define LED_PIN  D2        // GPIO pin connected to LED

void setup() {
    pinMode(PIR_SENSOR_PIN, INPUT); // Set PIR sensor pin as input
    pinMode(LED_PIN, OUTPUT);        // Set LED pin as output
    digitalWrite(LED_PIN, LOW);      // Ensure LED is off initially
    Serial.begin(115200);            // Start serial communication
}

void loop() {
    int motionDetected = digitalRead(PIR_SENSOR_PIN);

    if (motionDetected == HIGH) {
        digitalWrite(LED_PIN, HIGH); // Turn LED on
        Serial.println("Motion detected! LED ON");
    } else {
        digitalWrite(LED_PIN, LOW);  // Turn LED off
        Serial.println("No motion. LED OFF");
    }

    delay(500); // Small delay to avoid excessive readings
}

Last update: March 26, 2025