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MAX31865 Breakout board giving random numbers
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Please be positive and constructive with your questions and comments.

Re: MAX31865 Breakout board giving random numbers

by adafruit2 on Sat Feb 24, 2018 3:52 pm

ahhh! found the bug! try version 1.0.1 of the library, just pushed it

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Re: MAX31865 Breakout board giving random numbers

by mhxsol on Mon Feb 26, 2018 5:09 pm

Yes, problem solved.
Output is now:
RTD value: 7509
Ratio = 0.22915649
Resistance = 985.37292480
Temperature = -3.74

Great work, top service.

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Re: MAX31865 Breakout board giving random numbers

by kaushik18790 on Wed Mar 21, 2018 3:36 am

Dear Sir/Madam


I am also getting random values and they are keep on changing.
Attachments
RTD.png
RTD.png (166.64 KiB) Viewed 471 times

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Re: MAX31865 Breakout board giving random numbers

by adafruit_support_bill on Wed Mar 21, 2018 7:00 am

@kaushik18790 - Are you using version 1.0.1 of the library? It was just updated recently. https://github.com/adafruit/Adafruit_MAX31865

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Re: MAX31865 Breakout board giving random numbers

by paemail on Thu Mar 29, 2018 11:09 am

Dear Sir / Madam,

I am also getting random values with a Kemo DIN/EN60751 Class "B" Pt-100 RTD (3 wire) and max31865 on Adruino UNO (IDE 1.8.5). I've installed library version 1.0.1 but still have the problem.
Here is the code (Adafruit example):

Code: Select all | TOGGLE FULL SIZE
#include <Adafruit_MAX31865.h>

// Use software SPI: CS, DI, DO, CLK
Adafruit_MAX31865 max = Adafruit_MAX31865(10, 11, 12, 13);
// use hardware SPI, just pass in the CS pin
//Adafruit_MAX31865 max = Adafruit_MAX31865(10);

// The value of the Rref resistor. Use 430.0 for PT100 and 4300.0 for PT1000
#define RREF      430.0
// The 'nominal' 0-degrees-C resistance of the sensor
// 100.0 for PT100, 1000.0 for PT1000
#define RNOMINAL  100.0

void setup() {
  Serial.begin(115200);
  Serial.println("Adafruit MAX31865 PT100 Sensor Test!");

  max.begin(MAX31865_3WIRE);  // set to 2WIRE or 4WIRE as necessary
}


void loop() {
  uint16_t rtd = max.readRTD();

  Serial.print("RTD value: "); Serial.println(rtd);
  float ratio = rtd;
  ratio /= 32768;
  Serial.print("Ratio = "); Serial.println(ratio,8);
  Serial.print("Resistance = "); Serial.println(RREF*ratio,8);
  Serial.print("Temperature = "); Serial.println(max.temperature(RNOMINAL, RREF));

  // Check and print any faults
  uint8_t fault = max.readFault();
  if (fault) {
    Serial.print("Fault 0x"); Serial.println(fault, HEX);
    if (fault & MAX31865_FAULT_HIGHTHRESH) {
      Serial.println("RTD High Threshold");
    }
    if (fault & MAX31865_FAULT_LOWTHRESH) {
      Serial.println("RTD Low Threshold");
    }
    if (fault & MAX31865_FAULT_REFINLOW) {
      Serial.println("REFIN- > 0.85 x Bias");
    }
    if (fault & MAX31865_FAULT_REFINHIGH) {
      Serial.println("REFIN- < 0.85 x Bias - FORCE- open");
    }
    if (fault & MAX31865_FAULT_RTDINLOW) {
      Serial.println("RTDIN- < 0.85 x Bias - FORCE- open");
    }
    if (fault & MAX31865_FAULT_OVUV) {
      Serial.println("Under/Over voltage");
    }
    max.clearFault();
  }
  Serial.println();
  delay(10000);
}


And here is my setup:
IMG_20180329_165627_8.jpg
IMG_20180329_165627_8.jpg (757.06 KiB) Viewed 456 times


Any help is appreciated

Thank you in advance.

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Re: MAX31865 Breakout board giving random numbers

by adafruit2 on Thu Mar 29, 2018 11:12 am

follow the guide for 3-wire operation, you need to adjust the jumpers

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Re: MAX31865 Breakout board giving random numbers

by adafruit_support_bill on Thu Mar 29, 2018 11:17 am

If you are using a 3-wire probe, you need to set the 3-wire jumper as described here: https://learn.adafruit.com/adafruit-max ... re-sensors

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Re: MAX31865 Breakout board giving random numbers

by Delivery2you on Tue Sep 18, 2018 8:10 am

I have also issues with PT1000. It seems on your example you have some kind of capacitor between the 5V and GRN. It is not described anywhere in the wiring diagram.
I am using 5V exit pin on the Nano and when I put the code on, the voltage drops to 3.8 and below, from the initial reading of around 4.6V.
Attachments
Max31865IMG.png
Max31865IMG.png (836.25 KiB) Viewed 189 times

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Re: MAX31865 Breakout board giving random numbers

by adafruit2 on Tue Sep 18, 2018 12:45 pm

please use a breadboard, you aren't getting any data, something is amiss with your wiring

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Re: MAX31865 Breakout board giving random numbers

by Delivery2you on Tue Sep 18, 2018 1:10 pm

So, it seems, and now the code is giving me a different error. Which btw I got from the testing before.
Attachments
Max31865IMG.png
Max31865IMG.png (1006.75 KiB) Viewed 185 times

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Re: MAX31865 Breakout board giving random numbers

by adafruit2 on Tue Sep 18, 2018 1:19 pm

hiya - that product isnt from us its a clone - please contact the vendor for support :)

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Please be positive and constructive with your questions and comments.