FM Radio

Published: January 16, 2026

This project is an Arduino-powered FM radio that uses the TEA5767 radio module, an LCD1602 display, a rotary encoder for tuning, and a PAM8403 audio amplifier to drive a speaker. With this build, you can manually tune stations with the rotary knob, auto-seek the next available station with a button press, and listen through a connected speaker. It’s a compact DIY radio project that combines digital control with classic FM listening.

📸 Preview

⚙️ How It Works:

The Arduino UNO acts as the brain, controlling the TEA5767 FM radio module over the I²C bus.
The TEA5767 module handles the actual FM signal reception and outputs the audio signal through its 3.5 mm headphone jack.
A rotary encoder lets you tune the frequency manually.
Pressing the encoder button triggers an auto-seek to the next station.
The LCD1602 shows the tuned frequency.
PAM8403 amplifier powers a small speaker for audio output.

🧰 Parts & Materials Used

Component	Notes
Arduino UNO	Main microcontroller board
TEA5767 FM Radio Module	FM receiver, communicates via I²C
LCD1602 Display (16-pin)	Shows frequency and status
Rotary Encoder with Push Button	Manual tuning + auto-seek button
PAM8403 Audio Amplifier	Drives speaker output
3W 8Ω Speaker	Audio output
10k Potentiometer	LCD contrast control
3.5mm Male-to-Bare Wire Cable	Connects TEA5767 audio to amp
Breadboard + Wires	Prototyping
Power Source	USB or 5V battery bank

🔌 Wiring Instructions

TEA5767 Module → Arduino

TEA5767 Pin	Arduino Pin	Notes
VCC	5V	Module is 5V-tolerant
GND	GND	Common ground
SDA	A4	I²C data
SCL	A5	I²C clock

LCD1602 Display → Arduino

LCD Pin	Arduino Pin	Notes
VSS	GND	Ground
VDD	5V	Power
VO	Middle of Potentiometer	Contrast control
RS	D7	Register select
RW	GND	Always LOW (write mode)
E	D8	Enable
D4	D9	Data
D5	D10	Data
D6	D11	Data
D7	D12	Data
A	5V	Backlight +
K	GND	Backlight –

Rotary Encoder → Arduino

Encoder Pin	Arduino Pin
CLK	D2
DT	D3
SW	D4
+V	5V
GND	GND

PAM8403 Audio Amplifier

PAM Pin	Connection
Power +	Arduino 5V
Power –	Arduino GND
G	Black aux wire
B (R-in)	Red aux wire
Speaker +/-	To speaker terminals

🧾 Arduino Code

Language: C++

#include <Wire.h>
#include <LiquidCrystal.h>

// ------ LCD pins (RS, E, D4, D5, D6, D7) ------
LiquidCrystal lcd(7, 8, 9, 10, 11, 12);

// ------ Rotary encoder ------
const uint8_t ENC_A = 2;   // CLK
const uint8_t ENC_B = 3;   // DT
const uint8_t ENC_SW = 4;  // push button
volatile int8_t encDelta = 0;
volatile uint8_t lastAB = 0;

// ------ TEA5767 ------
const uint8_t TEA5767_ADDR = 0x60;      // I2C address
float freqMHz = 101.1;                   // start frequency
const float F_MIN = 87.0, F_MAX = 108.0;
const float STEP  = 0.1;                 // MHz
const uint8_t RSSI_THRESHOLD = 8;        // 0..15 (raise if it stops on noise)

// ---- helpers ----
void tea5767SetFrequency(float mhz) {
  uint16_t pll = (uint16_t)((4.0 * (mhz * 1000000.0 + 225000.0)) / 32768.0);
  uint8_t data[5];
  data[0] = (pll >> 8) & 0x3F;           // MUTE=0, SM=0
  data[1] = pll & 0xFF;
  data[2] = 0xB0;                        // HLSI=1, SSL mid, stereo
  data[3] = 0x10;                        // XTAL=1 (32.768kHz)
  data[4] = 0x08;                        // 50µs de-emphasis (UK/EU)
  Wire.beginTransmission(TEA5767_ADDR);
  Wire.write(data, 5);
  Wire.endTransmission();
}

bool tea5767Read(uint8_t buf[5]) {
  Wire.requestFrom((uint8_t)TEA5767_ADDR, (uint8_t)5); // explicit cast
  for (uint8_t i = 0; i < 5 && Wire.available(); i++) buf[i] = Wire.read();
  return true;
}

// RSSI (signal level) is in byte3[7:4] -> 0..15
uint8_t tea5767SignalLevel() {
  uint8_t r[5]; tea5767Read(r);
  return (r[3] >> 4) & 0x0F;
}

// optional “ready” flag: byte0 bit7
bool tea5767Ready() {
  uint8_t r[5]; tea5767Read(r);
  return (r[0] & 0x80) != 0;
}

void updateLCD() {
  lcd.setCursor(0, 0);
  lcd.print("Tuned: ");
  lcd.print(freqMHz, 1);
  lcd.print(" MHz   ");
}

void encISR() {
  uint8_t a = digitalRead(ENC_A);
  uint8_t b = digitalRead(ENC_B);
  uint8_t ab = (a << 1) | b;
  static const int8_t table[16] = {0,-1,+1,0,+1,0,0,-1,-1,0,0,+1,0,+1,-1,0};
  encDelta += table[(lastAB << 2) | ab];
  lastAB = ab;
}

void setup() {
  Wire.begin();
  pinMode(ENC_A, INPUT_PULLUP);
  pinMode(ENC_B, INPUT_PULLUP);
  pinMode(ENC_SW, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(ENC_A), encISR, CHANGE);
  attachInterrupt(digitalPinToInterrupt(ENC_B), encISR, CHANGE);

  lcd.begin(16, 2);
  lcd.print("Initializing...");
  delay(200);

  tea5767SetFrequency(freqMHz);
  lcd.clear(); updateLCD();
  lcd.setCursor(0, 1); lcd.print("Rotate: tune   ");
}

void loop() {
  // rotary tuning
  noInterrupts(); int8_t d = encDelta; encDelta = 0; interrupts();
  if (d != 0) {
    freqMHz += d * STEP;
    if (freqMHz < F_MIN) freqMHz = F_MIN;
    if (freqMHz > F_MAX) freqMHz = F_MAX;
    tea5767SetFrequency(freqMHz);
    updateLCD();
  }

  // button: auto-seek forward
  if (digitalRead(ENC_SW) == LOW) {
    lcd.setCursor(0, 1); lcd.print("Auto-seeking...");

    float start = freqMHz;
    while (true) {
      // step forward & wrap
      freqMHz += STEP;
      if (freqMHz > F_MAX) freqMHz = F_MIN;
      tea5767SetFrequency(freqMHz);
      delay(50);                   // small settle time

      // check signal strength
      uint8_t lvl = tea5767SignalLevel();
      if (lvl >= RSSI_THRESHOLD && tea5767Ready()) {
        updateLCD();
        lcd.setCursor(0,1);
        lcd.print("Signal ");
        lcd.print(lvl);
        lcd.print("         ");
        break;
      }

      // safety: stop if we wrapped around without finding anything
      if (fabs(freqMHz - start) < 0.001f) {
        lcd.setCursor(0,1); lcd.print("No station     ");
        break;
      }
    }
    delay(250); // debounce
  }
}

📝 Notes

Rotating the encoder adjusts frequency in 0.1 MHz steps.
Pressing the encoder triggers auto-seek to the next strong station.
Signal strength is evaluated using the TEA5767’s RSSI reading.
Use the amplifier’s physical knob to control volume.
Adjust the LCD’s contrast using the 10k potentiometer for best visibility.

💻 Upload the Code

Connect your Arduino UNO via USB.
Open Arduino IDE and select your board + port.
Paste the full FM Radio code into the IDE.
Click Upload.
Once uploaded, the LCD will show the frequency. Tune and listen!

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