10. Input devices¶
This week, we explored input devices and learned how to integrate them with a microcontroller. We worked on sensors as input devices and successfully integrated them into our microntroller.
To verify the sensor’s functionality, we monitored its data through the serial monitor and analyzed real-time readings. Additionally, we visualized the data using graphical representations, which helped us better understand the sensor's behavior and fluctuations over time.
Through this process, we gained hands-on experience in sensor interfacing, data acquisition, and visualization techniques.
1. Group Assignment¶
Probe an input device's analog levels and digital signals
2. Individual Assignment¶
Measure something: add a sensor to a microcontroller board that you have designed and read it
Sensors¶
A sensor is an electronic device that detects changes from Environment, such as temperature, light, motion, and ound, and converts them into electrical signals. These signals are then processed and used in various applications, including machines, electronic devices, and automated systems.
Analog signal sensors¶
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.
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); }
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.
Coding:
const int pin = 13;
void setup(){
Serial.begin(9600);
pinMode(pin , OUTPUT);
}
void loop(){
int foto = analogRead(A0)/4;
analogWrite(pin , foto);m
Serial.print(“val: “);
Serial.println(foto);
delay(100);
}
Digital signal¶
Experiment with Button
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.
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);
}