Input Device

A. What are Input Devices?

Input Devices are those components which allow person to enter data, command, signals into a computer or microcontroller. This helps to interact with the outside world by receiving information from users, sensor, or other systems.

What are sensors?

A sensor is a type of input device, but it’s special because it can feel or sense something around it — like:

heat
light
sound
touch
motion
pressure

The sensor detects something in the environment and sends data to the machine.

Group Assignment

For this week's group assignment, we focused on probing the digital signals from an input device using the serial plotter in the Arduino IDE. We chose the HC-SR04 ultrasonic sensor and connected it to the RP2040 breakout board that we had designed earlier.

Working as a group helped us divide tasks—some handled the wiring and connections, while others worked on the code and monitored the serial output. Using the serial plotter, we could see the distance values change in real time as we moved objects in front of the sensor. This made it easy to observe how digital sensors communicate through precise timing and pulse width.

Through this activity, I understood how digital sensors don’t just give HIGH/LOW states—they can encode continuous values using time-based signals. It was also a great opportunity to test and reuse the custom board we had worked on earlier.

For more detail, please visit Group assignment page

Individual Assignment

B. Trying Flex Sensor

I finally got to try out a flex sensor for the first time!

The plan was simple—if the sensor bends past a certain point, an LED should blink.

Making sure all the connections were easy. The sensor was hooked up to an analog pin, a 10KΩ resistor to GND, and an LED to a digital pin.

Connection

Component	Pin on Component	Connects To RP2040 Pin	Notes
Flex Sensor	One leg	3.3V	Power
Flex Sensor	Other leg	GP26 (A0)	Analog input & resistor here
10k Resistor	One leg	GP26 (A0)	Voltage divider setup
10k Resistor	Other leg	GND	Ground
LED (long leg)	Anode (+)	GP16 (D3)	Digital output
LED (short)	Cathode (-)	GND	Via 220Ω resistor if needed

But. this dd not work out. I tried changing codes thrice, but led wasn't blinking.

It was important to ensure that the processor which was in use, in arduiono IDE was installed in Library.

Since, code was not not working, planned to check indiviaually whether led, jumper connections, sensor were at right place. Went ahead by checking Serial Monitor.

Readings were between 2-3-4, but it should have been somewhere from 500-600. Here, error was found. Something was wrong with sensor connection input.

Then, figured out the working together which is documented on Sohan

C. Testing Button as Input

Since final project needs a button to trigger the camera, I wanted to test how a button works as an input on the RP2040 board. I connected a push button and an LED. When I press the button, the LED turns on — this acts like a test version of my camera trigger.

To make the connection safe and work properly, I added a 220Ω resistor with the LED. I also used INPUT_PULLUP in the code, which means I didn’t need an extra resistor for the button. This test helped me understand how digital inputs work and how to control output (like an LED) with a button press.

Connection

Component	RP2040 Pin	Notes
Button – leg 1	D2	Digital input pin with INPUT_PULLUP
Button – leg 2	GND	Connected to ground
LED – anode	D3	Connect with a 220Ω resistor
LED – cathode	GND	Connected to ground

D. Using a Potentiometer

In final project, the camera will include a zoom feature (either digital or mechanical). To control this smoothly and manually, I tested a potentiometer as a way to adjust the zoom level.

Turning the potentiometer changes the analog value (0 to 65535), which I can then map to control a zoom mechanism —like moving a lens forward and backward using a servo motor or stepper motor.

The potentiometer acts as a voltage divider. As you turn the knob, the middle pin outputs a voltage between 0V and 3.3V. The RP2040 reads this as an analog value from 0 to 65535 (16-bit resolution).

Connection

Component	Pin on Component	Connects To RP2040 Pin	Description
Potentiometer	Left (VCC)	3.3V	Power supply
Potentiometer	Right (GND)	GND	Ground
Potentiometer	Middle (Signal)	GP26 (A0)	Analog input (reads values)

E. Trying Out an LDR Sensor

The LDR is a simple sensor that changes resistance based on light intensity:

More light → less resistance

Less light → more resistance

Using this, can read light levels as analog values and use them to trigger different actions — like taking a photo when it gets dark, or adjusting brightness dynamically.

Connection

Component	Pin on Component	Connects To RP2040 Pin	Description
LDR	One leg	3.3V	Power supply
LDR	Other leg	GP26 (A0)	Analog input, shared with resistor
10k Resistor	One leg	GP26 (A0)	Forms voltage divider with LDR
10k Resistor	Other leg	GND	Connects to ground

The values ranged depending on light intensity.
When I covered the LDR, the values dropped.
When exposed to bright light or flashlight, values increased.

This gives me a reliable input method to track light levels — which I can later use to:

Auto-capture a photo in low light
Warn if lighting is too bright or dark
Control screen/display brightness

F. DHT11 Temperature Sensor

For this setup, I used a DHT22 sensor to read both temperature and humidity using my ESP32-S3 board, and I wanted to keep things clean without using a breadboard.

I connected the sensor directly using female jumper wires

Connection Table

DHT Sensor Pin	ESP32-S3 Pin	Description
VCC	3.3V	Power supply for the sensor
DATA	GPIO14 (any GPIO)	Digital data pin for communication
GND	GND	Ground connection
(Optional)	10kΩ Resistor	Between VCC and DATA as pull-up (if using raw sensor)

I used GPIO4 for the data pin, but you can pick any other digital pin if needed.

Libraries Installed (Arduino IDE):

To make the sensor work, I installed two libraries:

DHT sensor library by Adafruit
Adafruit Unified Sensor library

You can get them from Tools → Manage Libraries in Arduino IDE. Just search “DHT” and install the one by Adafruit.

Have tried few more input devices in Output Device Week

Customised RP2040 Board

Programming Process for Input Devices

When working with input devices like sensors on a microcontroller (such as ESP32 or Arduino), I followed a step-by-step programming process:

1.Importing Libraries

Some sensors need extra libraries to function properly. These libraries help the board understand how to communicate with the sensor.

2.Defining Pins

I assigned the correct pins on the microcontroller where the sensor or input device is connected. This helps the board know where to read the data from.

3.Setup Function

In the setup section, I prepared the board to start reading data. This includes starting the serial monitor (to see sensor readings) and setting up any necessary pin modes.

4.Loop Function

This part runs continuously. Here, I read the data from the input device or sensor again and again. Based on the values, I can decide what the system should do next—like turning on an LED, moving a motor, or printing the result.

Summary

The programming process included:

Adding libraries (only if needed)

Setting up pin connections

Initializing the system to start reading inputs

Continuously reading sensor data and responding

About the Code

The base code for the input device was generated using ChatGPT and served as a starting point. It was then modified to match the actual wiring and setup with the ESP32.

Key adjustments included:

Changing pin numbers according to the connections

Tuning delay values and thresholds for accurate sensor response

Removing unnecessary parts of the code

Adding simple logic to trigger outputs based on sensor input

The serial monitor was used to observe live readings and confirm the sensor's behavior. The final code was shaped through trial, error, and small tweaks to fit the project's specific needs

Original Code File

Push Button LED

Light Sensor

Potentiometer

Humidity Temperature Sensor