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SensorAmplifyer 3648 and Adalogger
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Please be positive and constructive with your questions and comments.

SensorAmplifyer 3648 and Adalogger

by HansH on Mon Apr 19, 2021 9:30 am

I want to collect data with an Adafruit Feather M0 Adalogger from the
Adafruit PT1000 RTD Temperature Sensor Amplifier - MAX31865 PRODUCT ID: 3648

As the Adafruit sensor-amplifyer is based on the MAX31865 chip, there occurs the question, if I should expect, to successfully run the same program on the Adalogger to evaluate sensor-amplifyer data from other breakout boards also based on the MAX31865?
I.e. does the chip define the requiered communication completely?

best regards Hans

HansH
 
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Re: SensorAmplifyer 3648 and Adalogger

by mikeysklar on Tue Apr 20, 2021 2:54 pm

Hans,

Can you restate your question another way. Your combination of using the Adalogger M0 and the P1000 #3648 is a fine combo. Would you be running CircuitPython or Arduino code? If you need to add more sensors you will need multiple MAX31865 devices, but the controller can handle that since they all sit on the SPI bus.

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Re: SensorAmplifyer 3648 and Adalogger

by HansH on Wed Apr 21, 2021 5:09 pm

Thank You for looking into my post and Your answer.

I'm quite new to programming microprocessors. So don't be surprised reading a beginner's question.

I guess, I'll start with Circuitpython for simplicity and avoiding tedious programming mistakes for my first steps, but I guess such a simple task like reading a PT1000 amplifyer would be also easily programmed in C++

I expect, I need to load a driver for the communication in the header of my program. I believe there is a library for Adafruit's MAX31865 PRODUCT ID: 3648, making available the commands for reading the the amplifyer.

Can I expect that this library will also work for MAX31865 based amplifyers?
I'm thinking of a MAX31865PMB1, a breakout board from MaximIntegrated, which has the advantage for me, that it has a smaller form factor as it is only 22mm wide.

best regards
Hans

HansH
 
Posts: 21
Joined: Wed Apr 14, 2021 2:49 pm

Re: SensorAmplifyer 3648 and Adalogger

by mikeysklar on Thu Apr 22, 2021 3:12 pm

Hans,

If you have not used the MAX31865 before I would definitely start with our guide and hardware to get yourself going quickly. CircuitPython is much easier. All it takes is four wires and a few lines of code to get going.

775F821E-4ADA-49DD-B79A-2ABC7D27BE23.png
775F821E-4ADA-49DD-B79A-2ABC7D27BE23.png (238.81 KiB) Viewed 132 times


Code: Select all | TOGGLE FULL SIZE
import time
 
import board
import busio
import digitalio
 
import adafruit_max31865
 
 
# Initialize SPI bus and sensor.
spi = busio.SPI(board.SCK, MOSI=board.MOSI, MISO=board.MISO)
cs = digitalio.DigitalInOut(board.D5)  # Chip select of the MAX31865 board.
sensor = adafruit_max31865.MAX31865(spi, cs)
# Note you can optionally provide the thermocouple RTD nominal, the reference
# resistance, and the number of wires for the sensor (2 the default, 3, or 4)
# with keyword args:
# sensor = adafruit_max31865.MAX31865(spi, cs, rtd_nominal=100, ref_resistor=430.0, wires=2)
 
# Main loop to print the temperature every second.
while True:
    # Read temperature.
    temp = sensor.temperature
    # Print the value.
    print("Temperature: {0:0.3f}C".format(temp))
    # Delay for a second.
    time.sleep(1.0)


https://learn.adafruit.com/adafruit-max ... cuitpython

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Re: SensorAmplifyer 3648 and Adalogger

by HansH on Thu Apr 22, 2021 3:58 pm

@mikeysklar

Thank You a lot for Your help. I'll try it as soon, as I have the material. And Yes, to separate out potential error causes, I've ordered for my initial tests the Adafruit sensor amplifyer. I'll try other amplifyers much later.
Yes, the script really looks like Python and is as easy to read and write. WIth C++ indeed, I'm not that familar. I'll try that later, some time after everything runs well with the CircuitPython.

Regarding the "import adafruit_max31865" driver:
I wonder if the Max31865 processor and the chosen reference resistor on the board completely define the communication with a Max31865 amplifyer, so that I could expect, I could move to other max31865 amplifyer boards. I think, in theory that should work, as long as the board's voltage is accepted to collaborate with the Adalogger. I guess, the SPI coding is generated in the Max31865 chip. Do You agree?

HansH
 
Posts: 21
Joined: Wed Apr 14, 2021 2:49 pm

Re: SensorAmplifyer 3648 and Adalogger

by mikeysklar on Fri Apr 23, 2021 2:09 pm

Using another essentially identical max31865 would probably be fine. I would be careful to not view off the part skew number by much as chips change with the most subtle name changes (eg. max31865a might not work at all with this library). The SPI protocol is two way so both the python side and the max31865 component are familiar with the protocol. You can look closer at the library for details as to what parts are supported.

https://github.com/adafruit/Adafruit_Ci ... ax31865.py

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Re: SensorAmplifyer 3648 and Adalogger

by HansH on Sat Apr 24, 2021 10:44 am

Thank You for the helpful and interesting details.

As mentioned, I need to insert the board into a tube with minimum diameter.
So another idea might be, to mechanically cut a few millimeters off the Adafruit's board in one dimension. Could You provide information for that, like the location of connecting lines within the board? (Probably it not obvious like in a single layered board?)

HansH
 
Posts: 21
Joined: Wed Apr 14, 2021 2:49 pm

Re: SensorAmplifyer 3648 and Adalogger

by mikeysklar on Mon Apr 26, 2021 10:26 am

The Downloads page off the guide has the PCB layout and design files so you can see all the traces.

https://learn.adafruit.com/adafruit-max ... /downloads

9E34DBD6-DF7B-4001-9940-1F68287ADDC2.png
9E34DBD6-DF7B-4001-9940-1F68287ADDC2.png (45.19 KiB) Viewed 93 times

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Re: SensorAmplifyer 3648 and Adalogger

by HansH on Mon Apr 26, 2021 11:25 am

@mikeysklar
Thank You for the plot. Sorry I didn't know, You had already published it on the website.

I looks like I could cut off the 1" width down the feather board's 0.9" width, without cutting any connection.

But .... there are these two singular +poles, popping through the boards upper surface. The connection of these poles isn't visible in the plot. May be it's another layer of the board?
So I'm not shure, if abrading or cutting the amplifyer board to that smaller 0.9" dimension, (touching these isolatedly standing +poles) will state a problem.

HansH
 
Posts: 21
Joined: Wed Apr 14, 2021 2:49 pm

Please be positive and constructive with your questions and comments.