my final goal is to use python (spidev) to communicate with a BMS chip. Until now I was quite unsuccessful, thats why I wanted to use piscope to track the activity of the SPI pins.

The device is not connected atm. and the SPI GPIO pins are show activity, is that normal and ok ?

"Screenshot of piscope showing GPIO pin 7-11"

  • SCK and MOSI pins will be active if anything tells them to transfer data. The other side of SPI bus being connected or not has no relevance. Or have I misunderstood the question? – domen Feb 14 '19 at 9:07
  • but why is MOSI doing sth. when it is not even connected ? Why is it not just constantly Low / High ? – Unsigned Student Feb 14 '19 at 9:33
  • How is rpi supposed to know something is connected or not? It's same as GPIO, you can drive it high or low, and just measure its level, and it will be the same no matter what is connected (well, unless there's a low resistance path to Vcc or GND, which there should not be). – domen Feb 14 '19 at 10:11
  • check out some of the RPI GPIO libraries. Some pins have pullups, pulldown or have floating currents. See some PINout diagrams containing 3V 5V, GND, SPI, etc – Colin Rosati Feb 14 '19 at 16:04
  • Ok thank you guys I think I understood it now :) – Unsigned Student Feb 15 '19 at 1:58

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