First swing at calibration.  It appears that my MAX31865 assembly is reading the RTD resistance incorrectly.  I checked it with a multimeter, and it comes out to about 100 ohms when submerged in an icewater bath, like it should (after accounting for the wires).  But the value coming back from the registers indicates about 95 ohms.  This method sorta works but not quite - it corrects fine for 0C but not 100C.
First swing at calibration.  It appears that my MAX31865 assembly is reading the RTD resistance incorrectly.  I checked it with a multimeter, and it comes out to about 100 ohms when submerged in an icewater bath, like it should (after accounting for the wires).  But the value coming back from the registers indicates about 95 ohms.  This method sorta works but not quite - it corrects fine for 0C but not 100C.

Also fixed a bug when measuring near 0C.

jwalthour/sensors