There's two breakout sides, the left side has the power and data lines. On the right side, theres a terminal block breakout for connecting up a thermocouple wireset.
- GND is the common ground line. You will need to connect this to both your power ground and microcontroller 'data reference' ground. If you are using '1-Wire' parasitic power you still need to connect this to your microcontroller
- VIN is 3-5V power in if you are not using parasitic power. If you want to power the sensor, connect up 3-5V DC power here, the MAX31850 will automagically switch to external power instead of parasitic power
- 3V3 This is the 3.3V output from the onboard regulator - you can get up to 100mA from it. It is only used if you are externally powering. In parasitic mode, it is unused and there will be no voltage available
A 4.7K resistor must be connected between this pin and 3V3 power. For parasitic power, the resistor lives over on the microcontroller side of the data line. For external-power it can be on either side of the data line.
The other side of the board has a breakout for a 3.5mm terminal block, included in the mini kit. Use the screw terminal to connect to the thermocouple as thermocouple wires cannot be soldered to!
Remember, this kit is for K-type thermocouples only!