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#include <Wire.h>

uint16_t freq = 1015;

void setup() {
  Wire.begin();

  qn8035_init();
  qn8035_set_freq(freq);            // test 101.5 MHz
}

void loop() {
}

void qn8035_init() {
  Wire.beginTransmission(0x10);
  Wire.write(0x00);
  Wire.write(0b10000000);           // reset to the default values
  Wire.endTransmission();

  Wire.beginTransmission(0x10);
  Wire.write(0x14);
  Wire.write(0b00000111);           // no mute, 50 us, GAIN_DIG[2:0] = 0 dB, GAIN_ANA[2:0] = 0 dB
  Wire.endTransmission();
}

void qn8035_set_freq(uint16_t m_freq) {  // frequency * 10, e.g. 105.8 MHz -> 1058
  uint16_t d = (m_freq - 600) * 2;  // d = (m_freq - 60) / 0.05;

  Wire.beginTransmission(0x10);
  Wire.write(0x07);
  Wire.write(d & 0xFF);             // CH[7:0], FM channel: CH = (60 + CH * 0.05) MHz
  Wire.endTransmission();

  Wire.beginTransmission(0x10);
  Wire.write(0x0A);
  Wire.write((d >> 8) & 0x03);      // CH[9:8], Highest 2 bits of 10-bit channel index: CH = (60 + CH * 0.05) MHz
  Wire.endTransmission();

  Wire.beginTransmission(0x10);
  Wire.write(0x00);
  Wire.write(0b00010001);           // RXREQ = 1 -> enter receive mode, CH is determined by CH[9:0]
  Wire.endTransmission();
}