Adafruit_SPIDevice does not drive MOSI pin

[ilka-schulz]

I have tried this library on an ESP32-WROVER as well as on an Arduino Uno R4 Minima and on both platforms this library does not drive the MOSI pin (observed with oscilloscope). It does drive CS and SCLK but not MOSI. Thus, the MAX31865 does not respond...

• Arduino board: Arduino Uno R4 Minima

• Arduino IDE version (found in Arduino -> About Arduino menu): 2.1.1 (also using PlatformIO makes no difference)

• List the steps to reproduce the problem below:

  • attach Adafruit MAX31865 board to any Arduino device, e.g. Arduino Uno R4 Minima
    • attach the MAX31865 board to power or not, makes no difference
    • choose either HardwareSerial with the fixed pins or use SofwareSerial and specify pins
    • with SoftwareSerial, choose any pin for MOSI you like and pass it to the Adafruit_MAX31865 constructor
    • connect Arduino board's MOSI to MAX31865 or not, makes no difference
    • call pinMode(MOSI_PIN, OUTPUT); in void setup() or not, it makes no difference
  • run example code from this repository
  • attach an oscilloscope to all four pins and set trigger to falling edge on CS
  • observe how CS falls and SCLK goes up and down beautifully
  • observe how MOSI stays high the entire time

Should I cross-post this issue on Adafruit_BusIO?

[cyberwaelder1]

Same problem here