Pinouts

The MAX31850K breakout is not too complicated, we'll go thru all the pins so you can be familiar with them!
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.

Power Pins

There are three power pins: VIN GND 3V3
  • 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

Address Pins

The A0 A1 A2 A3 pins are address pins. Please note these do not affect the 1-Wire 'fixed address'! These pins set bits that can be read from the 'configuration' register. These are used in case you have up to 16 different boards and you want to identify which is which without having to look up which has what address since the 1Wire address is burned into ROM. They are by default shorted to ground. You can tie them to 3.3V by cutting the back traces between the 3-way jumpers and then soldering the jumper the 'other' way or tying the pins to 3V or GND.

Data Pin

Ah finally the data pin. This is a '1-Wire' device so all data is transmitted and received on a single pin which is pretty cool. It is also possible for the microcontroller to provide power to the sensor on this line - triple duty! This pin is 3V logic level, and must be connected to a 3V output pin. Arduino's are not 3V, they're 5V so a level shifter is required, see the next pages for details.

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.

Themocouple Breakout


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!
This guide was first published on Feb 26, 2014. It was last updated on Oct 16, 2018. This page (Pinouts) was last updated on May 04, 2015.