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MAX31856 on Raspberry pi 4 : Temperature = 0,0
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MAX31856 on Raspberry pi 4 : Temperature = 0,0

by Monsieur_x on Fri May 01, 2020 10:46 am

Hello everyone!

As part of an internship project, I have to use a MAX31856 module from adafruit. This module is a CAN amplifier
which has the ability to read any type of thermocouple.
To begin I try to perform this operation on a thermocouple. However, I am not a regular user of the
raspberry Pi.
I own the model Raspberry Pi 4+.
I followed the following tutorial https://cdn-learn.adafruit.com/download ... lifier.pdf
by doing the steps on the raspberry part.
So I did download the latest version of the bundle. I then recovered the necessary modules either:
adafruit_max31856.mpy
adafruit_bus_device
I transferred both of those files to /lib.

And on the balance sheet when I run the simple.py test I get 0.0 as you can see on the first figure.

Image



Then I run a defect detection program given in the downloaded library and I get the second picture.

Image

Finally I checked the connections several times, I bought a new part thinking that maybe I had made a short circuit but still nothing.

Thank you for your help!

Monsieur_x
 
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Re: MAX31856 on Raspberry pi 4 : Temperature = 0,0

by adafruit_support_carter on Fri May 01, 2020 7:19 pm

I transferred both of those files to /lib.

You should install the libraries using pip:
https://learn.adafruit.com/adafruit-max ... ibrary-5-9

Do you have a thermocouple actually attached to the MAX31856?

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Re: MAX31856 on Raspberry pi 4 : Temperature = 0,0

by Monsieur_x on Sat May 02, 2020 10:51 am

Yes i used sudo pip3 install adafruit-circuitpython-max31856


Of course, i've got a thermocouple attached on the MAX31856

Monsieur_x
 
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Re: MAX31856 on Raspberry pi 4 : Temperature = 0,0

by Monsieur_x on Sat May 02, 2020 11:45 am

Maybe this will help you. I used the debug.

Image

Monsieur_x
 
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Re: MAX31856 on Raspberry pi 4 : Temperature = 0,0

by Monsieur_x on Mon May 04, 2020 1:39 pm

Hello ! i send a picture with the electrical mounting
(Thermocouple is'nt connected on the white breadboard

Image
Thx

Monsieur_x
 
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Re: MAX31856 on Raspberry pi 4 : Temperature = 0,0

by adafruit_support_carter on Mon May 04, 2020 1:47 pm

Can you post another photo showing the soldering on the breakout headers.
soldering.jpg
soldering.jpg (30.62 KiB) Viewed 43 times

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Re: MAX31856 on Raspberry pi 4 : Temperature = 0,0

by Monsieur_x on Mon May 04, 2020 2:56 pm

Image
Image

i use this

Image

Monsieur_x
 
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Re: MAX31856 on Raspberry pi 4 : Temperature = 0,0

by adafruit_support_carter on Mon May 04, 2020 7:22 pm

Are they not soldered on? If not, you'll need to do that to be able to communicate with the breakout.
https://learn.adafruit.com/adafruit-gui ... aq-3028525

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Re: MAX31856 on Raspberry pi 4 : Temperature = 0,0

by Monsieur_x on Tue May 05, 2020 12:18 pm

thank you for the answer! I'll get that soldered today. I'll get back to you to let you know if after the welds it's working.

Monsieur_x
 
Posts: 12
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Re: MAX31856 on Raspberry pi 4 : Temperature = 0,0

by Monsieur_x on Tue May 05, 2020 3:43 pm

Thank you very much! Now it is well connected.
When I launch the bug file it shows me that the sensor is powered on. Now however the thermocouple shows me this temperature.

Image

Monsieur_x
 
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Re: MAX31856 on Raspberry pi 4 : Temperature = 0,0

by adafruit_support_carter on Tue May 05, 2020 4:01 pm

What type of thermocouple are you using?

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Re: MAX31856 on Raspberry pi 4 : Temperature = 0,0

by Monsieur_x on Tue May 05, 2020 4:34 pm

i've S type and K type but I think type K is broken. Besides, the point of my topic is to use type S

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Re: MAX31856 on Raspberry pi 4 : Temperature = 0,0

by adafruit_support_carter on Tue May 05, 2020 5:03 pm

The default type when not specified is Type K:
https://github.com/adafruit/Adafruit_Ci ... 56.py#L139

If you are using a Type S, change this line:
Code: Select all | TOGGLE FULL SIZE
thermocouple = adafruit_max31856.MAX31856(spi, cs)

to this:
Code: Select all | TOGGLE FULL SIZE
thermocouple = adafruit_max31856.MAX31856(spi, cs, adafruit_max31856.ThermocoupleType.S)

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Re: MAX31856 on Raspberry pi 4 : Temperature = 0,0

by Monsieur_x on Tue May 05, 2020 6:11 pm

I got the same result after changing the line

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Re: MAX31856 on Raspberry pi 4 : Temperature = 0,0

by adafruit_support_carter on Tue May 05, 2020 6:41 pm

Please post a photo of your soldering on the header pins.

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Please be positive and constructive with your questions and comments.