10. Input Devices¶
Assignment
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.
Learning outcomes
- Demonstrate workflows used in sensing something with input device(s) and MCU board
Have you answered these questions?
- Linked to the group assignment page.
- Documented what you learned from interfacing an input device(s) to your microcontroller and optionally, how the physical property relates to the measured results.
- Documented your design and fabrication process or linked to the board you made in a previous assignment.
- Explained the programming process(es) you used.
- Explained any problems you encountered and how you fixed them.
- Included original design files and source code.
- Included a ‘hero shot’ of your board.
Potentiometer
A potentiometer is a three-terminal resistor with a rotating or sliding contact that acts as an adjustable voltage divider. It’s often used for things like volume control or brightness adjustment. As part of my assignment, I experimented with a potentiometer to understand how it works as an input device for microcontrollers.
I connected the middle (wiper) pin of the potentiometer to analog input A1 of my board, and the two outer pins to VCC and GND. This allowed me to read varying voltage levels depending on the knob’s position. Here’s the code I used to read analog values.
As I turned the knob, the analogRead(A1) function returned values between 0 and 1023, which represent the voltage between 0V and 5V. These readings were printed to the serial monitor, allowing me to observe how the values changed in real time.
Next, I used the potentiometer to control an LED’s brightness using Pulse Width Modulation (PWM). I connected the LED to digital pin 6.
The map() function scaled the analog input to a range suitable for PWM (0 to 255), and analogWrite() adjusted the LED’s brightness accordingly. Turning the potentiometer now let me dim or brighten the LED in a smooth, continuous way.
Through this process, I learned how the potentiometer can serve as a simple yet powerful analog input, useful for controlling various outputs or user interfaces in interactive electronic projects.
Experiment with potentiometer
Coding:
void setup(){
Serial.begin(9600);
//Serial.print(” Hello world “); } void loop(){
int val = analogRead(A1);
Serial.println(val);
delay(200);
}
const int led = 6;
void setup(){
Serial.begin(9600);
pinMode(led , OUTPUT);
//Serial.print(” Hello world “); }
void loop(){
analogWrite(led , 25); }
Video from Vimeo¶
Button
A button is a basic digital input device with two states: pressed and not pressed. In my assignment, I connected a push-button to digital pin 2 and used the internal pull-up resistor to keep the input stable when not pressed. With INPUT_PULLUP, the pin reads HIGH when the button is not pressed and LOW when pressed. I used a simple program to read the button state and display it in the serial monitor, which helped me understand how digital input works.
To make the interaction visual, I connected an LED to pin 6 and modified the code so the LED turns on when the button is pressed. This made it easy to see the button’s effect and also introduced me to the concept of debouncing, where button presses can cause brief flickers due to mechanical noise. Using the button this way helped me understand how to trigger and control events in an electronic project.
Experiment with Button
Coding:
const int led = 13;
const int button = 8;
void setup(){
Serial.begin(9600);
pinMode(led , OUTPUT);
pinMode(button , INPUT_PULLUP);
} void loop(){
int val = digitalRead(button);
Serial.println(val);
if(val == 0){
digitalWrite(led , 1);
} else{
digitalWrite(led , 0);
}
Light Sensor
A light sensor (like a photoresistor or LDR) is an analog input device that changes its resistance based on the amount of light hitting it. In my assignment, I connected the light sensor to analog pin A1 to measure varying light levels. When the light increases, the resistance drops, resulting in a higher voltage and a higher analog reading (closer to 1023). I used a simple code to read and print the sensor values, allowing me to observe how light intensity affects the readings.
To make the output interactive, I connected an LED to pin 6 and used the light sensor to control its brightness. I mapped the analog values from the sensor to a PWM range (0–255) and used analogWrite() to adjust the LED accordingly. This allowed the LED to brighten in the dark and dim in bright light. It was a great way to explore how analog sensors can be used to create responsive, light-based interactions in a circuit.
Experiment with Light Sensor
Coding: const int pin = 13;
void setup(){
Serial.begin(9600);
pinMode(pin , OUTPUT);
}
void loop(){
int foto = analogRead(A0)/4;
analogWrite(pin , foto);
Serial.print(“val: “);
Serial.println(foto);
delay(100);
}
Tilt Sensor Module
A tilt sensor module is a simple digital input device used to detect orientation or movement. In my assignment, I connected the tilt sensor to digital pin 2 to check whether it was tilted or in a steady position. Inside the module is a small metal ball that shifts when tilted, making or breaking a connection. When upright, the circuit is open and the sensor reads LOW; when tilted, the ball closes the circuit and the pin reads HIGH. I used a basic program to read and display the tilt status through the serial monitor.
To visualize the tilt, I connected an LED to pin 6 and programmed it to turn on when the sensor detected movement. This way, tilting the module triggered the LED, acting like a basic motion switch. The tilt sensor was an easy yet effective way to explore movement detection in physical computing and understand how simple digital sensors can be used in interactive or safety-related applications.
Experiment with Tilt Sensor Module
Coding:
const int pin = 13;
const int sensor = 7;
void setup(){
Serial.begin(9600);
pinMode(pin , OUTPUT);
pinMode(sensor , INPUT);
}
void loop(){
int val = digitalRead(sensor);
Serial.println(val);
}
