I am planning to use the spi0 of the raspberry 4 B+. My system is super fresh: enter image description here

  1. Factory-new Raspberry just unboxed
  2. Flashed Raspian
  3. Booted Raspberry
  4. Connected my Digital analyser
  5. PIN24 is sending some undifined binarys

For the use of SPI0 i need PIN24 as the chip selection pin.

Why is it sending and what is it sending? What kind of Protocol is it?

enter image description here

  • Raspbian is a 32bit OS. Don't know this Raspian.
    – Milliways
    Feb 12 at 9:18

1 Answer 1


On an unmodified system GPIO 8 (pin 24) will be configured as an input.

It will have weak pulls to ground enabled but in effect it is floating - especially if your probe wires are acting like an aerial.

  • Thanks for the hint. My analyser was not connected to the raspberry ground. So everything was floating. Once grounded it shows me the correct spi signals.
    – thomas0721
    Feb 12 at 14:09

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