MAX31844 AdaFruit board with Thermo K

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tekati
 
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MAX31844 AdaFruit board with Thermo K

Post by tekati »

I purchased the board and sensor from adafruit

https://www.adafruit.com/products/269 and https://www.adafruit.com/products/270

I have a Arduino Mega 2560 Rev 3 with the following code.

Code: Select all

/*************************************************** 
  This is an example for the Adafruit Thermocouple Sensor w/MAX31855K

  Designed specifically to work with the Adafruit Thermocouple Sensor
  ----> https://www.adafruit.com/products/269

  These displays use SPI to communicate, 3 pins are required to  
  interface
  Adafruit invests time and resources providing this open source code, 
  please support Adafruit and open-source hardware by purchasing 
  products from Adafruit!

  Written by Limor Fried/Ladyada for Adafruit Industries.  
  BSD license, all text above must be included in any redistribution
 ****************************************************/

#include "Adafruit_MAX31855.h"

int thermoDO = 5;
int thermoCS = 6;
int thermoCLK = 7;

Adafruit_MAX31855 thermocouple(thermoCLK, thermoCS, thermoDO);
  
void setup() {
  Serial.begin(9600);
  
  pinMode(2, OUTPUT);
  pinMode(3, INPUT);
  pinMode(4, OUTPUT);
  digitalWrite(2, HIGH);
  digitalWrite(4, LOW);
  
  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);
}
I have the board hooked up to pins Digital 3-7 starting with VIN on Pin 3 and CLK on Pin 7

This is what I get on the Serial Window.

Code: Select all

MAX31855 test
Internal Temp = 0.00
C = 0.00
F = 32.00
Internal Temp = 0.00
C = 0.00
F = 32.00
Internal Temp = 0.00
C = 0.00
F = 32.00
Internal Temp = 0.00
C = 0.00
F = 32.00
Internal Temp = 0.00
C = 0.00
F = 32.00
My Thermocouple has very short leads but yellow and red are hooked up properly.

The strange thing is I get Internal Temp of 0.00 which tells me there is something strange going on regardless of the thermocoupler.

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adafruit_support_bill
 
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Re: MAX31844 AdaFruit board with Thermo K

Post by adafruit_support_bill »

I have the board hooked up to pins Digital 3-7 starting with VIN on Pin 3 and CLK on Pin 7
The code you posted is ouputting VIN on pin 2. Can you post a photo showing your connections?

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tekati
 
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Re: MAX31844 AdaFruit board with Thermo K

Post by tekati »

Sorry you are correct. I just have the adapter stuck straight onto the mega. Not a exciting picture. I skipped pins 0 and 1 as those are used for communications. So yes 2-7

2 vin
3 3.3v out
4 gnd
5 do
6 cs
7 clk

The board has 6 pins with the labels.

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adafruit_support_bill
 
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Re: MAX31844 AdaFruit board with Thermo K

Post by adafruit_support_bill »

Looks like the example from the previous version of the library. There was a bug-fix update a few days ago. You should download the latest.

Also, please post a photo showing your soldering.

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tekati
 
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Re: MAX31844 AdaFruit board with Thermo K

Post by tekati »

I just downloaded the drivers yesterday so if changes were made a couple days ago that wont be it.

Here are the solder joints.
Attachments
Solder 6 pin
Solder 6 pin
photo3.jpg (707.81 KiB) Viewed 1109 times
Solder 6 pin
Solder 6 pin
photo2.jpg (786.38 KiB) Viewed 1109 times
Solder 2 pin
Solder 2 pin
photo1.jpg (654.38 KiB) Viewed 1109 times

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tekati
 
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Re: MAX31844 AdaFruit board with Thermo K

Post by tekati »

Here is the connection to the Mega v3 pictures.
Attachments
Top view
Top view
photo6.jpg (483.07 KiB) Viewed 1109 times
Side view
Side view
photo5.jpg (689.1 KiB) Viewed 1109 times
Side view showing position
Side view showing position
photo4.jpg (702.67 KiB) Viewed 1109 times

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tekati
 
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Re: MAX31844 AdaFruit board with Thermo K

Post by tekati »

Here is a shot from my Parallax configured as follows.

DO Blue Channel 1 shows peaks at 3.3v
CLK Red Channel 2 shows peaks at 5v (Is this right?)
CS Trigger Channel

Things do not look right here.
Attachments
Therm Error.jpg
Therm Error.jpg (91.76 KiB) Viewed 1107 times

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tekati
 
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Re: MAX31844 AdaFruit board with Thermo K

Post by tekati »

Also just confirmed I have the latest library.

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tekati
 
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Re: MAX31844 AdaFruit board with Thermo K

Post by tekati »

Okay I think I see the problem. Correct me if I am wrong but my board is missing a 1N4148 Diode.

Do you not test these boards before sending them out? I would have thought this would have been caught in quality control???
Attachments
photo1-fubar.jpg
photo1-fubar.jpg (577.69 KiB) Viewed 1107 times

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adafruit_support_bill
 
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Re: MAX31844 AdaFruit board with Thermo K

Post by adafruit_support_bill »

That does look like the cause of the problem there. Contact [email protected] with a link to this thread for a replacement. I'll follow up with our testers in QC.

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Re: MAX31844 AdaFruit board with Thermo K

Post by adafruit »

Not sure how this could have passed our test - we test each board fully - perhaps it was broken off during shipment? thanks for the heads up!

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