K type Thermocouple/Uno/MAX31855 query

Absolute newbie – so please pardon my incorrect terminology. Trying to understand what I need to do here to read a temp.

Platform: Arduino Uno
Amp: MAX 31855
Thermocouple: K type thermocouple
All products from adafruit.

Have read the information posted related to the above products - but seem to be missing something in the hookup:
MAX31855 amplifier has 6 pins labeled thusly:
→ Vin
← 3Vo
→ GRD
← DO
→ CS
→ CLK

Thermocouple connected to terminal posts by color.

Instructions indicate that VCC goes to 3-5 V, and that GND goes to GND. Additionally, it indicates that 3 connections are to be made to 3 digital pins of the Uno.

From the layout, it does not appear that the MAX 31855 can “plug directly into” the UNO (as per a shield) – pin arrangement does not seem to line up.

If I am incorrect here – please advise. If not, allow me to continue.

Assuming the connections are to be made via a breadboard, I proceeded down that avenue, with the UNO plugged into the desktop via USB.

MAX31855 UNO
Vin <-> UNO 5V
3Vo Nothing here
GND <-> UNO GRN
DO <-> UNO Pin 8
CS <-> UNO Pin 9
CLK <-> UNO Pin 10

Uploaded the MAX31855 text via the Arduino interface, then opened the serial monitor.

Could see the MAX31855 initialize then begin its cycle with the following readout:

MAX31855 test
Internal Temp = 0.00
C = 0.00
Internal Temp = 0.00
C = 0.00
Internal Temp = 0.00
C = 0.00
Internal Temp = 0.00
C = 0.00
etc

Again – I am in the very early stages of trying to learn this. Any comments, suggestions, corrections would be most appreciated.

Thanks!

keninar

Hi, javascript:void(0); The MAX31855 datasheet clearly states the part is 3.3v with an 'Absolute Maximum' rating of 3.6v..., you may have already blown the ic I'm sorry to say.

Cy, he's using the Adafruit breakout which has a 3V regulator onboard.

keninar, can you post your code?

this may come a little late, however for what its worth: like the before mentioned, must use 3.3v, on the 31855 . BUT there is a catch though! the catch is: the max31855 uses 3.3v LOGIC and the UNO uses 5v logic. in other words you can/WILL "lockout" your Microprocessor. i "locked out" 2 MCU's before i figured it out. :( the solution is to power the MCU at 3.3v if you can, so the logic levels are the same. the other solution is to use a TXB0104 level translator.

good luck.