I used a MAX31865 3 wire PT 100 and the MAX31865 board connected to the wemos D1 mini,
but the values are wrong in initial phase, if I disconnect the power from 31865 and reconnect it, the values are correct after that, but if I do reboot the complete system, the error occurs again.
Does someone know this issue , or have a solution / hint ?
Using Adafruit sample with Adafruit MAX31865 LIB 1.1.0 / 1.2.0 same problem with both versions
#include <Adafruit_MAX31865.h>
// Use software SPI: CS, DI, DO, CLK
Adafruit_MAX31865 thermo = Adafruit_MAX31865(D8, D7, D6, D5); // D8 pull down 10k
(tried to use Wemos Pins D1 - D4 but the same result)
.....
initial values :
RTD value: 26930
Ratio = 0.82183838
Resistance = 353.39050293
Temperature = 726.32
after reconnect power of MAX31865 module
RTD value: 8291
Ratio = 0.25302124
Resistance = 108.79913330
Temperature = 22.59
BUG resolved :
Bug found :
I missed to cut thin trace for 3 wired connection 
You will have to cut the thin trace in between the 2-way jumper on the right side of the board, and then solder closed the blob on the right side