I’m attempting to communicate with multiple DWM1001Cs over SPI on the same bus to a Teensy 4.1. Each DWM1001 has its own CS line, but of course share the MISO, MOSI and CLK lines. The Teensy is powered off of a 5V switcher and the DWMs are powered by a 3.3V regulator powered by the 5V line.
The problem that I am seeing is the the MISO line isn’t dropping below about 1.6V when the DWM is responding, which causes the communication to be garbled at best.
Is there something I’m missing? Should there be a pulldown on the MISO line? Or?
EDIT: I’ve looked at the bus both using a Saleae and an o-scope. The Saleae and o-scope show the CS, CLK and MOSI lines working as expected. The o-scope shows the MISO line with what appears to be good data, just going from 3.3V-1.6V instead of 3.3V-0V.