Arduino Uno and Leonardo SPI clock can't be measured I want to measure the SPI clock (pin 13) using the Arduino example code for the SPI library (very simple example). Basically independent from the loop function, the clock should be fired continuously.

I deployed the Arduino SPI example code on the board and measured pin 13 on an oscilloscope, but nothing was found, always zero volt.
Please note the SPI clock will only be active while it is shifting data. So simply put the spi.transfer in a hard loop

#include &lt;SPI.h&gt;

void setup() {
  SPI.begin();
  while (1) {
    SPI.transfer(0x00);
  } 
}