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MAX31850 to TeensyNet™ Converter Board

The Adafruit MAX31850 Breakout Board (BoB) is a new product that allows the use of K-type thermocouples on 1-Wire® mini-lans. The MAX31850 has built-in cold junction compensation, does the analog-to-digital conversion, has a much wider temperature range, and is easily implemented in 1-Wire® software schemes.

The only downside for the TeensyNet™ is that it’s a 3.3v device, and so can’t be directly connected to the TeensyNet™’s 5v mini-lan. That’s where my level converter board comes in:

My level converter board uses a simple level converter circuit that uses two BS170 MOSFETs and two 10k resistors to convert the 5v TeensyNet™ mini-lan to a safe 3V3 level for the MAX31850. It derives the 3V3 from the BoB’s on-board regulator.

The latest version of TeensyNet.ino supports the new board. The bare board is available from OSHPark in multiples of three, at a very reasonable price.

One final caveat. The BoB will not work with grounded thermocouples, so select your thermocouples wisely.