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Topic: MAX31855 K Type Thermocouple Breakout Board Temperature 1350°C for 3V-5V (Read 315 times) previous topic - next topic

c1000mg

I purchased few of these boards from China and haven't been able to make it work with any available Arduino libraries, https://www.ebay.com/itm/222202249304

I get the following serial readings:

MAX31855 test
Internal Temp = 23.37
Something wrong with thermocouple!
2
nan
Internal Temp = 23.37
Something wrong with thermocouple!
2
nan
Internal Temp = 23.37
Something wrong with thermocouple!
2
nan
Internal Temp = 23.37
Something wrong with thermocouple!
2
nan
Internal Temp = 23.44
Something wrong with thermocouple!
2
nan


I added code Serial.println(thermocouple.readError()) and I get 2 And nan for the temperature readings and the wrong temperature for the internal temperature.

I was wondering if anyone had any luck making this boards work with Arduino?

Thank you

pylon

Did you read the sticky post at the top of the topic list?

Post your complete code (use code tags!) and links to the used libraries (the IDE provides at least two libraries for these chips, you might have used another one). And post a wiring diagram of your setup (may be hand drawn).

c1000mg

sorry, but I posted late night...

I used Adafruit MAX31855 library https://github.com/adafruit/Adafruit-MAX31855-library


Code: [Select]

#include <SPI.h>
#include "Adafruit_MAX31855.h"

// Default connection is using software SPI, but comment and uncomment one of
// the two examples below to switch between software SPI and hardware SPI:

// Example creating a thermocouple instance with software SPI on any three
// digital IO pins.
#define MAXDO   12
#define MAXCS   9
#define MAXCLK  13

// initialize the Thermocouple
Adafruit_MAX31855 thermocouple(MAXCLK, MAXCS, MAXDO);

// Example creating a thermocouple instance with hardware SPI
// on a given CS pin.
//#define MAXCS   10
//Adafruit_MAX31855 thermocouple(MAXCS);

void setup() {
  while (!Serial); // wait for Serial on Leonardo/Zero, etc

  Serial.begin(9600);

  Serial.println("MAX31855 test");
  // wait for MAX chip to stabilize
  delay(500);
}

void loop() {
  // basic readout test, just print the current temp
   Serial.print("Internal Temp = ");
   Serial.println(thermocouple.readInternal());

   double c = thermocouple.readCelsius();
   if (isnan(c)) {
     Serial.println("Something wrong with thermocouple!");
     Serial.println(thermocouple.readError());
          Serial.println(c);

   } else {
     Serial.print("C = ");
     Serial.println(c);
   }
   //Serial.print("F = ");
   //Serial.println(thermocouple.readFarenheit());

   delay(1000);
}




outsider

Appears the TC is connected backwards, the red wire is NEGATIVE.

c1000mg


JohnLincoln

Have a look at this thermocouple colour code. The red wire is negative in the US.

It even says red is negative on the PCB photo.

c1000mg

red is normally negative but the other wire is green in that case red should be positive, and i took the connector that came with it and red is positive and green is negative... will i have problems if i reverse the polarity?

c1000mg

After doing a long and detailed research about this product i came around the following forum discussion...
https://www.reddit.com/r/AskElectronics/comments/5w62lk/max31855_is_this_aliexpress_failure_fixable/

looks like this was made for both chip 6675 and 31855 and thy have different pins description, T- in the 6675 should be connected to ground and in the 31855 should not be connected to ground... and I think thats why i'm getting the error!!

but if anyone made any modification please let me know until i get the real deal!! thank you

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