Group Assignment:

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

Hero Shot

Input Devices

The objective of this project is to design, develop, and test an electronic input device using an Infrared (IR) sensor to control an RGB LED. As part of my Fab Academy 2025 assignment on input devices, this project demonstrates how sensor data can be used to influence output behavior. The IR sensor detects the presence or proximity of an object and sends an analog or digital signal to a microcontroller. This signal is then interpreted to control the color or intensity of an RGB LED, enabling real-time interaction between input and output components. The project involves designing a custom PCB in KiCad, programming the microcontroller to read IR sensor data, and writing logic to control the RGB LED based on sensor input. This assignment enhances my understanding of sensor integration, analog/digital signal processing, and embedded control, contributing to my overall goal of mastering digital fabrication and interactive electronics.

Why I Used ESP32-C3 for Input Week I selected the ESP32-C3 module as the microcontroller for input device testing due to its robust wireless communication, rich peripheral support, and efficient processing capabilities. It supports multiple input interfaces like analog sensors, joysticks, and buttons, enabling real-time data acquisition and wireless transmission.

Technical Specifications — ESP32-C3

Pinout Overview — ESP32-C3

Digital I/O (GPIO0–GPIO21)

• All pins support digital I/O, PWM, pull-up/down, and peripheral functions.
• GPIOs support 20–40 mA output current (dependent on function).
• GPIO0: Used for boot mode during flashing.
• GPIO1 (TX), GPIO3 (RX): Default UART.
• GPIO9 & GPIO10: Typically connected to internal flash — avoid for I/O.
• GPIO19 & GPIO20: USB D- and D+ (for native USB).

Analog Input (ADC1)

• Channels: 6 ADC inputs (GPIO0 to GPIO5)
• Resolution: 12-bit
• Voltage Range: 0–3.3V

The Seeed Studio XIAO Series offers ultra-compact, powerful microcontroller boards ideal for rapid prototyping and embedded projects in FabLabs and personal studios. With variants like XIAO RP2040, ESP32C3, and nRF52840, they provide built-in USB, multiple GPIOs, and support for Arduino, CircuitPython, and PlatformIO. Their tiny form factor (21x17.5 mm) and versatile features make them perfect for wearables, IoT, and interactive devices. Each board includes castellated pads for easy soldering to custom PCBs. **Download the official Seeed Studio XIAO Series PDF here:** [https://files.seeedstudio.com/wiki/XIAO\_SERIES/res/XIAO-Series-Datasheet.pdf](https://files.seeedstudio.com/wiki/XIAO_SERIES/res/XIAO-Series-Datasheet.pdf)

The Seeed Studio XIAO Series System on Module (SoM) user manual provides comprehensive guidance for using compact, high-performance microcontroller boards designed for prototyping, embedded applications, and educational use. The XIAO series includes variants like XIAO SAMD21, XIAO RP2040, XIAO ESP32C3, and XIAO nRF52840, each offering unique features such as built-in USB, low power consumption, wireless connectivity (Wi-Fi, BLE), and versatile development environment support (Arduino, PlatformIO, CircuitPython). The manual covers essential topics such as pin configuration, power management, memory specs, programming modes, and firmware flashing procedures. With castellated edges and a small form factor (21 x 17.5 mm), XIAO modules are ideal for wearable electronics, IoT devices, and student projects. The document also includes hardware schematics, PCB layout, and application guidelines to support integration into custom designs, making it a valuable reference for FabAcademy students.

Components List with Explanation

Digital Inputs

This Arduino project reads a digital input from pin 10 and controls two LEDs connected to pin 9 and pin 2. Depending on the input state, the appropriate LED blinks every second.

Code Explanation:

• Pin 10: Set as INPUT, used to detect a digital signal (e.g., from a switch).
• Pin 9: Set as OUTPUT, turns ON/OFF when input is HIGH.
• Pin 2: Set as OUTPUT, turns ON/OFF when input is LOW.

Arduino Code:

void setup()
{
    pinMode(9, OUTPUT);   // Output 1
    pinMode(2, OUTPUT);   // Output 2
    pinMode(10, INPUT);   // Input
}

void loop()
{
    if (digitalRead(10) == HIGH)
    {
        digitalWrite(9, HIGH);
        digitalWrite(2, LOW);  // Ensure other LED is off
        delay(1000);
        digitalWrite(9, LOW);
        delay(1000);
    }
    else
    {
        digitalWrite(2, HIGH);
        digitalWrite(9, LOW);  // Ensure other LED is off
        delay(1000);
        digitalWrite(2, LOW);
        delay(1000);
    }
}
    

Note: If using a pushbutton or switch on pin 10, ensure proper pull-up or pull-down resistors are used to prevent floating input states.

For my Fab Academy Input Devices assignment, I designed a simple interactive system using an IR (Infrared) sensor to control an RGB LED light strip. The IR sensor acts as the input device, continuously emitting and detecting infrared signals. Under normal conditions, when the IR beam is not obstructed, the system interprets this as a "clear" state. In response, the RGB LED light strip remains active, cycling through colors or blinking continuously using PWM (Pulse Width Modulation) signals controlled by the Seeed Studio XIAO ESP32-C3 microcontroller.

When an object blocks the IR sensor (such as a hand or any solid object), the IR receiver detects the absence of the reflected signal. This triggers a change in logic on the ESP32, which is programmed to immediately turn off the RGB LED strip. This simulates an interactive response where user presence or motion alters the lighting behavior. The RGB LED remains off until the IR sensor is no longer blocked. This project demonstrates how digital input sensing and PWM-controlled outputs can be combined in real-time interaction using simple components. It also highlights the practical use of microcontrollers to bridge input sensing and visual feedback in creative applications.

Files download here