#include <Wire.h>
#define RDA5807_ADDR 0x10
void setup()
{
  Wire.begin();
  Serial.begin(9600);
  tuneFrequency(1030);  // Tune to 103.0 MHz, BNR, Sofia
}
void loop() {
}
void tuneFrequency(float frequency) {
  uint16_t freqReg = (uint16_t)((frequency - 87.5) * 100);
  uint16_t freq = (freqReg + 10) << 2;
  uint16_t controlReg = 0x0000;
  controlReg |= 0x0340;
  writeRegister(0x00, controlReg);
  writeRegister(0x02, freq);
  uint16_t status = readRegister(0x01);
  Serial.print("Status Register: ");
  Serial.println(status, HEX);
}
void writeRegister(uint8_t reg, uint16_t data) {
  Wire.beginTransmission(RDA5807_ADDR);
  Wire.write(reg);
  Wire.write(data >> 8);
  Wire.write(data & 0xFF);
  Wire.endTransmission();
}
uint16_t readRegister(uint8_t reg) {
  Wire.beginTransmission(RDA5807_ADDR);
  Wire.write(reg);
  Wire.endTransmission();
  Wire.requestFrom(RDA5807_ADDR, 2);
  uint16_t data = (Wire.read() << 8) | Wire.read();
  return data;
}

#include <Wire.h>
double f_ini = 103; // БНР 103 МHz София
void setup()
{
  Wire.begin();
  setFrequency(f_ini);
}
void loop()
{
}
void setFrequency(double fmhz)
{
  int frequencyB = 4 * (fmhz * 1000000 + 225000) / 32768;
  char frequencyH = frequencyB >> 8;
  char frequencyL = frequencyB & 0XFF;
  Wire.beginTransmission(0x60);
  Wire.write(frequencyH);
  Wire.write(frequencyL);
  Wire.write(0xB8);
  Wire.write(0x10);
  Wire.write((byte)0x00);
  Wire.endTransmission();
}

#include <avr/io.h>
#include <util/delay.h>
#define RDA5807_ADDR 0x10
#define FREQ_REGISTER 0x03
void i2c_start() {
  PORTB &= ~0x08;
  PORTB &= ~0x10;
}
void i2c_stop() {
  PORTB |= 0x10;
  PORTB |= 0x08;
}
void i2c_write(uint8_t data) {
  for (uint8_t i = 0; i < 8; i++) {
    PORTB = (data & 0x80) ? (PORTB | 0x08) : (PORTB & ~0x08);
    PORTB |= 0x10; PORTB &= ~0x10; data <<= 1;
  }
}
void rda5807_init() {
  i2c_start(); i2c_write(RDA5807_ADDR << 1);
  i2c_write(0x00); // Reset
  i2c_write(0x81); // Enable, mono
  i2c_write(FREQ_REGISTER); i2c_write(0x3C); // 103.00 MHz
  i2c_stop();
}
int main(void) {
  DDRB |= 0x18; // Set SDA, SCL as output
  PORTB |= 0x18;
  rda5807_init();
  while (1);
}

void i2c_stop() {
  PORTB |= 0x10;
  PORTB |= 0x08;
}