MAX31865 threshold trouble (esp8266 NodeMCU v1)

Hello everyone,

I got myself a breakout board, named MAX31865 Dual PT-100 RTD (this one: I connected it with the Tinxi NodeMcu v1 in order to send temp values via WIFI to my java program.

The webserver is running without any problems, but I have so far been unable to get any values from the MAX31865… I first tried using the MAX31865 library (attached .cpp/.h) and the example code of it (attached file) but the only value I got is an error message: 255 high threshold…why??

Concerning the wiring: NodeMCU - MAX31865
3V3 - VIN
SD0 - SD0
D1 - CS1
SD1 - SD1
D0 - CS2

Please be patient with my knowledge, I’m a newbee at this sector :wink: If there are any other questions please ask!


  • PT100 (2-Wire; if working a 4-Wire will be used)
  • MAX31865
  • NodeMcu v1 esp8266

nodemcu_server_read.ino (2.1 KB)

MAX31865.cpp (6.89 KB)

MAX31865.h (4.54 KB)