/// Arduino FM receiver with TEA5767
/// Source: local TEA5767 Arduino package example.
/// Compatibility note: old Wire.send()/Wire.receive() calls were updated to
/// Wire.write()/Wire.read() for current Arduino IDE versions.

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

unsigned char search_mode = 0;

int b = 0;
int c = 0;

#define Button_next 6
#define Button_prev 7

unsigned char frequencyH = 0;
unsigned char frequencyL = 0;

unsigned int frequencyB;
double frequency = 0;
double freq_available = 0;

LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() {
  Wire.begin();
  lcd.begin(16, 2);

  pinMode(Button_next, INPUT);
  digitalWrite(Button_next, HIGH);

  pinMode(Button_prev, INPUT);
  digitalWrite(Button_prev, HIGH);

  frequency = 87.5;
  frequencyB = 4 * (frequency * 1000000 + 225000) / 32768;
  frequencyH = frequencyB >> 8;
  frequencyL = frequencyB & 0XFF;

  delay(100);

  Wire.beginTransmission(0x60);
  Wire.write(frequencyH);
  Wire.write(frequencyL);
  Wire.write(0xB0);
  Wire.write(0x10);
  Wire.write(0x00);
  Wire.endTransmission();

  delay(100);
}

void loop() {
  unsigned char buffer[5];

  lcd.setCursor(0, 0);
  Wire.requestFrom(0x60, 5);

  if (Wire.available()) {
    for (int i = 0; i < 5; i++) {
      buffer[i] = Wire.read();
    }

    freq_available = (((buffer[0] & 0x3F) << 8) + buffer[1]) * 32768 / 4 - 225000;

    lcd.print("FM ");
    lcd.print((freq_available / 1000000));

    frequencyH = ((buffer[0] & 0x3F));
    frequencyL = buffer[1];

    if (search_mode) {
      if (buffer[0] & 0x80) search_mode = 0;
    }

    if (search_mode == 1) lcd.print(" SCAN");
    else lcd.print("       ");

    lcd.setCursor(0, 1);
    lcd.print("Level: ");
    lcd.print((buffer[3] >> 4));
    lcd.print("/16 ");

    if (buffer[2] & 0x80) lcd.print("STEREO   ");
    else lcd.print("MONO   ");
  }

  if (!digitalRead(Button_next) && !b) {
    frequency = (freq_available / 1000000) + 0.05;
    frequencyB = 4 * (frequency * 1000000 + 225000) / 32768 + 1;
    frequencyH = frequencyB >> 8;
    frequencyL = frequencyB & 0XFF;

    Wire.beginTransmission(0x60);
    Wire.write(frequencyH);
    Wire.write(frequencyL);
    Wire.write(0xB0);
    Wire.write(0x1F);
    Wire.write(0x00);
    Wire.endTransmission();

    b = 100;
  }

  if (!digitalRead(Button_next) && b == 1) {
    search_mode = 1;

    Wire.beginTransmission(0x60);
    Wire.write(frequencyH + 0x40);
    Wire.write(frequencyL);
    Wire.write(0xD0);
    Wire.write(0x1F);
    Wire.write(0x00);
    Wire.endTransmission();

    b = 100;
  }

  if (!b == 0) b--;

  if (!digitalRead(Button_prev) && !c) {
    frequency = (freq_available / 1000000) - 0.05;
    frequencyB = 4 * (frequency * 1000000 + 225000) / 32768 + 1;
    frequencyH = frequencyB >> 8;
    frequencyL = frequencyB & 0XFF;

    Wire.beginTransmission(0x60);
    Wire.write(frequencyH);
    Wire.write(frequencyL);
    Wire.write(0xB0);
    Wire.write(0x1F);
    Wire.write(0x00);
    Wire.endTransmission();

    c = 100;
  }

  if (!digitalRead(Button_prev) && c == 1) {
    search_mode = 1;

    Wire.beginTransmission(0x60);
    Wire.write(frequencyH + 0x40);
    Wire.write(frequencyL);
    Wire.write(0x50);
    Wire.write(0x1F);
    Wire.write(0x00);
    Wire.endTransmission();

    c = 100;
  }

  if (!c == 0) c--;
}