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Appendix: Component Guide

This component guide provides a quick reference for the electronic parts included in the STEMAIDE Coder-Kit. Use it to understand their functions, identify their pins, and review safety guidelines.

Microcontroller Board & Prototyping

Arduino Uno R3

  • Description: The "brain" of your projects. It contains a microcontroller chip (ATmega328P) that executes instructions loaded from your computer.
  • Operating Voltage: 5V (powered via USB or 7-12V external jack).
  • Pins:
    • Digital Pins 0-13: Binary input/output pins. Pins marked with ~ support PWM (analog-like) output.
    • Analog Pins A0-A5: Read continuous voltage values (0V to 5V) and convert them to numbers (0 to 1023).
    • Power Pins: 5V, 3.3V, GND (Ground - 0V return reference), and Reset.

Breadboard

  • Description: A solderless prototyping grid used to temporarily connect components and wires.
  • Internal Connections:
    • Outer Rails (+ and -): Connected vertically down the entire length of the board. Used for distributing power (5V) and Ground (GND).
    • Inner Rows (1 to 30 or 60): Five holes in a row (columns A to E, and F to J) are connected horizontally. Inserting wires into the same row links them electrically.
    • Center Channel: A divider separating columns E and F. It isolates the two halves of the board, allowing you to mount integrated circuits or push buttons without shorting their opposite pins.

Inputs & Sensors

Push Button (Tactile Switch)

  • Description: A simple momentary switch that completes a circuit when pressed.
  • Usage: Digital input (ON/OFF).
  • Safety Tip: Use the internal INPUT_PULLUP resistor pin mode to prevent "floating" inputs (erratic signals caused by electromagnetic noise).

Light Dependent Resistor (LDR)

  • Description: A photoresistor whose electrical resistance decreases when light shines on it.
  • Usage: Analog sensor to detect ambient brightness.
  • Wiring: Wired as a voltage divider using a 10kΩ resistor, converting resistance changes into readable voltage levels on analog pin A0.

HC-SR04 Ultrasonic Distance Sensor

  • Description: Emits high-frequency sound pulses and measures the time it takes for the echo to return to calculate distance.
  • Pins:
    • VCC: Connects to 5V.
    • Trig: Sends trigger pulse (OUTPUT).
    • Echo: Outputs a pulse width matching echo time (INPUT).
    • GND: Connects to Ground.
  • Range: 2cm to 400cm.

Sound Sensor Module

  • Description: A microphone module that detects ambient sound pressure.
  • Pins:
    • AO: Analog output (indicates real-time sound amplitude).
    • DO: Digital output (goes HIGH if sound level crosses a potentiometer-adjusted threshold).
    • VCC & GND: Power connection (5V).

Outputs & Actuators

Light Emitting Diode (LED)

  • Description: A semiconductor light source that only conducts current in one direction (polarity sensitive).
  • Identification:
    • Anode (Positive): Longer leg. Connects to the Arduino control pin.
    • Cathode (Negative): Shorter leg. Connects to GND.
  • Resistor Requirement: Always connect a 220Ω resistor in series to limit current and prevent the LED from burning out.

RGB LED Module

  • Description: A combined package containing Red, Green, and Blue LEDs sharing a common pin.
  • Type: Common Cathode (common pin connects to GND).
  • Usage: Connect R, G, and B pins to PWM pins on the Arduino through individual 220Ω resistors to control and mix colors.

Traffic Light Module

  • Description: A custom PCB featuring Red, Yellow, and Green LEDs aligned in a vertical pillar.
  • Pins: Four pins labeled GND (common cathode), R, Y, and G. Connects directly to Arduino output pins without needing external breadboard resistors (current-limiting resistors are built directly into the module board).

Piezo Buzzer

  • Description: An audio output device that produces sound alerts.
  • Polarity: The positive lead (usually marked with a + symbol or longer leg) connects to the control pin. The negative lead connects to GND.

SG90 Servo Motor

  • Description: A rotary actuator that can turn precisely to any angle between 0 and 180 degrees.
  • Wired Connections:
    • Brown Wires: Ground (GND).
    • Red Wires: Power (5V).
    • Orange Wires: Signal (PWM commands from Arduino).