Olimexino 32u4: Wire.endTransmission() hangs I'm trying to get a TAE5767 (FM radio) to work. According to this instructable I'm trying it on a 5V-Olimexino 32u4 (Leonardo-compatible) with following code (Arduino 1.6.3):

#include &lt;Wire.h&gt;

void setFrequency(float frequency) {
  unsigned int frequencyB = 4 * (frequency * 1000000 + 225000) / 32768;
  byte frequencyH = frequencyB &gt;&gt; 8;
  byte frequencyL = frequencyB &amp; 0xFF;
  Wire.beginTransmission(0x60); 

  Wire.write(frequencyH);
  Wire.write(frequencyL);
  Wire.write(0xB0);
  Wire.write(0x10);
  Wire.write(0x00);
  Serial.println("sending");
  Wire.endTransmission();
  Serial.println("sent");
}

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

  Wire.begin();
  setFrequency(89);
}

void loop() {
}


Unfortunately, it only prints

sending


First, I thought I'd damaged my chip, but I'm now using the second with the same result. I've also tried the I2C-Scanner from Nick Gammon, but it prints nothing. I've tried adding 2.2k resistors from SCL and SDA to 5V without success. Does someone has a clue what I can try?
I've did not got it working with Wire. Hence I've implemented a I2C protocol myself using bit-banging and then it works.

Update from 2017-September-16

The problem was not Wire.h but a specialty of the Olimexino 32u4 board. I've only found out by using a Real Time Clock connected to the UEXT port's I2C bus, that I have to switch on the power for the UEXT port by setting D8 to LOW. Otherwise SDA or SCL seem to be pulled down preventing any I2C communication.