Description: The SparkFun MAX31855K Thermocouple Breakout is a simple 14-bit resolution, SPI-compatible, serial interface thermocouple digitizer that makes reading a wide range of temperatures possible. A thermocouple works by taking two wires made of dissimilar metals, connecting them at the two ends, and making a temperature gradient between one end and the other (a ‘hot’ end and a ‘cold’ one). Once this is achieved, a voltage potential is formed and current flows. The SparkFun Thermocouple Breakout takes a standard Type-K thermocouple in one end, digitizes the temperature measured and sends that data out the other end via a SPI interface, thereby interpreting the data and translating it for you to read!
With the SparkFun Thermocouple Breakout, the thermocouple’s hot junction can be read from -200°C to +700°C with an accuracy of ±2°C while the cold junction, inside the MAX31855K, can only range from -20°C to +85°C while maintaining ±2°C accuracy. The MAX31855K constantly measures the temperature of the cold junction using an internal temperature-sensing diode. The MAX31855K requires a power source from +3.0V to +3.6V (+3.0V nominal) and only draws 1.5mA maximum.
The Thermocouple Breakout is designed to accept a standard thermocouple connector, for convenience and compatibility with probes you may already own. These connectors aren’t necessary, and you could solder a thermocouple directly into the through holes labeled ‘+’ and ‘-’. If you decide to solder the thermocouple directly to the breakout board, it is recommended that the thermocouple be mounted for strain relief to avoid breaking the thin wires. Notches for a zip-tie or wire wrapping have been provided in the PCB opposite the header for this purpose.
Based on 5 ratings:
1 of 1 found this helpful:
Using two of these to pull box/internalMeat temperature for an electric smoker on RaspberryPi. Works great!
1 of 1 found this helpful:
Just connected it to an ESP8266 Thing Dev board. Using it to monitor the temperature of a pottery kiln. It will operate above the temperature range listed in the description. It was reading within 5-10F of the kiln controller at 1950 degrees F (the two thermocouples were in slightly different locations).
2 of 2 found this helpful:
It gave good and accurate readings (was comparing it to a commercial unit) and was very responsive. Log files also show that it reacted quicker than the commercial unit, and when it spiked to 770 as my device burst into flame, I was able to record the demise of my electronics very accurately. Only complaint is that while the device itself said +700 C, most of the components around it melt way before that. I recommend the thermocouple, and advise against lighting your electronics on fire.
Talked SPI to my ESP8266 right off the bat and now I can read the temperature of my pizza oven from inside the house.
I’m a tremendous fan of SparkFun but this breakout needs work. The direct connections for the thermocouple aren’t predrilled which risks damaging the board, there is no built in voltage leveling limiting the microcontrollers you can use unless you want to add a voltage leveler to your project. The “-” and “+” on the board should also be labeled “red” and “yellow”–going on the web there is a lot of misinformation about how the color coding works for thermocouples. Documentation is poor added to the breakout labeled cs, nc, so, sck when it would be a lot simpler to go with clk, cs, do. If you are going to use it with a pro-mini you’ll get it to work but my guess most people want it for more sophisticated applications.