I need to reduce the SPI clock speed of the Arduino Due down to about 100 kHz. Unfortunately my hardware doesn't support higher speeds.

With the current maximum divider of 255, I can only reach a speed of still 320 kHz (SPI.setClockDivider(10, 255);).

Of course I could use a software SPI, but I'm still interested in using the build-in hardware. A possible solution could be to lower the overall clock speed of 84 MHz. Any idea how to achieve this?

1 Answer 1


You can try using the SPISettings interface:

SPISettings settings(100000, MSBFIRST, SPI_MODE0);

... do your stuff ...
  • Very interesting, it seemed that "setDataMode()" function didn't work correctly, just with SPISettings interface I got the correct mode. Additionally I had to slow down the CS line. The SPI speed was ok in my case. Thanks!
    – Thomas
    Nov 30, 2015 at 19:55

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