Interfacing the NEG RGB LCD to display thermocouple readings from MAX 31855

General project help for Adafruit customers

Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.
Locked
odoyo
 
Posts: 5
Joined: Thu Jun 14, 2012 2:41 pm

Interfacing the NEG RGB LCD to display thermocouple readings from MAX 31855

Post by odoyo »

can anybody help with the sketch for interfacing the RGB LCD shield with the MAX 31855 amplifier to get thermocouple readings using a stand alone arduino uno.

User avatar
adafruit_support_bill
 
Posts: 88090
Joined: Sat Feb 07, 2009 10:11 am

Re: Interfacing the NEG RGB LCD to display thermocouple readings from MAX 31855

Post by adafruit_support_bill »

What help do you need? Post your current sketch and describe what it does or doesn't do for you.

odoyo
 
Posts: 5
Joined: Thu Jun 14, 2012 2:41 pm

Re: Interfacing the NEG RGB LCD to display thermocouple readings from MAX 31855

Post by odoyo »

I was just using the example for the max 31855 to get the thermocoulple reading and was getting weird results of like 6 degrees and -200 while I'm at a room temperature of about 24.

Code: Select all

#include "Adafruit_MAX31855.h"

int thermoDO = 3;
int thermoCS = 4;
int thermoCLK = 5;

Adafruit_MAX31855 thermocouple(thermoCLK, thermoCS, thermoDO);
  
void setup() {
  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!");
   } else {
     Serial.print("C = "); 
     Serial.println(c);
   }
   //Serial.print("F = ");
   //Serial.println(thermocouple.readFarenheit());
 
   delay(1000);
is something wrong with the library or is their something i need to change?

User avatar
adafruit_support_bill
 
Posts: 88090
Joined: Sat Feb 07, 2009 10:11 am

Re: Interfacing the NEG RGB LCD to display thermocouple readings from MAX 31855

Post by adafruit_support_bill »

The thermocouple amplifier is very sensitive and the readings can be affected by electrical noise. Keep the thermocouple probe away from other wiring and use the shortest wire possible.

User avatar
adafruit_support_rick
 
Posts: 35092
Joined: Tue Mar 15, 2011 11:42 am

Re: Interfacing the NEG RGB LCD to display thermocouple readings from MAX 31855

Post by adafruit_support_rick »

Looks like there was a bug in the 31855 library.

Delete the old version and download the new version. See if that helps.

User avatar
adafruit_support_bill
 
Posts: 88090
Joined: Sat Feb 07, 2009 10:11 am

Re: Interfacing the NEG RGB LCD to display thermocouple readings from MAX 31855

Post by adafruit_support_bill »

Looks like there was a bug in the 31855 library.
That affected readings below 0C (32F)

Scirocco
 
Posts: 1
Joined: Wed May 16, 2012 3:44 pm

Re: Interfacing the NEG RGB LCD to display thermocouple readings from MAX 31855

Post by Scirocco »

Hello,

I'm getting very similar results to the OP. -2000 deg C, to about 10 deg C at room temperature. It seems like it's discontinuous between -2000 to 6 deg C, switching back and forth rapidly. Was there ever a resolution to the problem?

Scirocco

User avatar
adafruit_support_bill
 
Posts: 88090
Joined: Sat Feb 07, 2009 10:11 am

Re: Interfacing the NEG RGB LCD to display thermocouple readings from MAX 31855

Post by adafruit_support_bill »

The amp is very sensitive to noise, which can result in unstable readings. You can try putting a 0.1uF or 0.01uF capacitor in parallel with the thermocouple probe in the screw-terminal block to tame the noise.

adafruit
 
Posts: 12151
Joined: Thu Apr 06, 2006 4:21 pm

Re: Interfacing the NEG RGB LCD to display thermocouple readings from MAX 31855

Post by adafruit »

Scirocco wrote:Hello,

I'm getting very similar results to the OP. -2000 deg C, to about 10 deg C at room temperature. It seems like it's discontinuous between -2000 to 6 deg C, switching back and forth rapidly. Was there ever a resolution to the problem?

Scirocco
make sure to download the latest library - we had a few bugs with negative temp readings. delete the old library completely

Locked
Please be positive and constructive with your questions and comments.

Return to “General Project help”