40. Project: Potentiometer Control

This lesson uses: Arduino UNO R3 board, TinkerBlock TK08 Rotary Potentiometer module, TinkerBlock TK02 RGB LED or TK37, jumper wires (or breadboard). Project: use potentiometer to control output; outcome: knob controls LED brightness (or buzzer pitch), serial shows potentiometer value and brightness/frequency.

1. Project goal

Build a potentiometer control system:

• Turn potentiometer: control LED brightness (or buzzer pitch)
• Higher potentiometer value → brighter LED (or higher pitch)

2. Wiring

Option 1: LED brightness

• TK08 Potentiometer: GND → GND, VCC → 5V, SIGNAL → A0
• TK02 RGB LED: GND → GND, RED → D3, GREEN → D5, BLUE → D6

Option 2: Buzzer pitch

• TK08 Potentiometer: GND → GND, VCC → 5V, SIGNAL → A0
• TK37 Passive Buzzer: GND → GND, VCC → 5V, SIGNAL → D3

3. Program structure

Same as last lesson: two fixed blocks setup() and loop().

• setup(): Start serial (optional); runs once.
• loop(): Keep repeating “read potentiometer → convert to brightness/pitch → set output → wait → repeat”.

Option 1: knob sets LED brightness. Option 2: knob sets buzzer frequency. Pick one and the knob “controls” the output.

4. Code to write

Option 1: LED brightness

// Option 1: Potentiometer → LED brightness
#define POT_PIN A0
#define LED_PIN 3    // PWM pin

void setup() {
  pinMode(LED_PIN, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  int potVal = analogRead(POT_PIN);
  int brightness = map(potVal, 0, 1023, 0, 255);   // Map to 0-255
  analogWrite(LED_PIN, brightness);
  Serial.print("Pot: ");
  Serial.print(potVal);
  Serial.print(" | Brightness: ");
  Serial.println(brightness);
  delay(50);
}

Option 2: Buzzer pitch

// Option 2: Potentiometer → buzzer frequency
#define POT_PIN A0
#define BUZZER_PIN 3

void setup() {
  Serial.begin(9600);
}

void loop() {
  int potVal = analogRead(POT_PIN);
  int frequency = map(potVal, 0, 1023, 200, 2000);   // Map to 200-2000 Hz
  tone(BUZZER_PIN, frequency);
  Serial.print("Pot: ");
  Serial.print(potVal);
  Serial.print(" | Freq: ");
  Serial.println(frequency);
  delay(50);
}

Program notes

Overall idea: analogRead gives 0–1023; use map(value, 0, 1023, outMin, outMax) to map to brightness 0–255 or frequency 200–2000 Hz, then analogWrite or tone. Review analog input controlling PWM/pitch.

5. Hands-on

1. Choose Option 1 or Option 2
2. After entering the code, click Verify (✓) to compile
3. Click Upload (→) to upload to the board
4. Turn the potentiometer:
   • Option 1: LED brightness follows potentiometer
   • Option 2: Buzzer pitch follows potentiometer
5. Try yourself: control different colors on RGB LED

Expected result: Turning the potentiometer changes LED brightness or buzzer pitch.

Proceed to Lesson 41.

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