It's easy to use the MCP9601 thermocouple amplifier with CircuitPython or Python, and the Adafruit CircuitPython MCP9600 module.  This module allows you to easily write Python code that reads the temperature from the sensor.

You can use this sensor with any CircuitPython microcontroller board or with a computer that has GPIO and Python thanks to Adafruit_Blinka, our CircuitPython-for-Python compatibility library.

CircuitPython Microcontroller Wiring

First wire up a MCP9601 to your board exactly as shown below. Here's an example of wiring a Feather M4 to the sensor with I2C:

  • Board 3V to sensor VIN (red wire)
  • Board GND to sensor GND (black wire)
  • Board SCL to sensor SCL (yellow wire)
  • Board SDA to sensor SDA (blue wire)

Python Computer Wiring

Since there's dozens of Linux computers/boards you can use we will show wiring for Raspberry Pi. For other platforms, please visit the guide for CircuitPython on Linux to see whether your platform is supported

Here's the Raspberry Pi wired with I2C:

  • Pi 3V3 to sensor VIN (red wire)
  • Pi GND to sensor GND (black wire)
  • Pi SCL to sensor SCL (yellow wire)
  • Pi SDA to sensor SDA (blue wire)
The MCP9601 uses the MCP9600 library. The code works the same for both!

Python Installation of MCP9600 Library

You'll need to install the Adafruit_Blinka library that provides the CircuitPython support in Python. This may also require enabling I2C on your platform and verifying you are running Python 3. Since each platform is a little different, and Linux changes often, please visit the CircuitPython on Linux guide to get your computer ready!

Once that's done, from your command line run the following command:

  • pip3 install adafruit-circuitpython-mcp9600

If your default Python is version 3 you may need to run 'pip' instead. Just make sure you aren't trying to use CircuitPython on Python 2.x, it isn't supported!

CircuitPython Installation of MCP9600 Library

Next you'll need to install the Adafruit CircuitPython MCP9600 library on your CircuitPython board.  

Click the Download Project Bundle button below to download the necessary libraries and the code.py file in a zip file. Extract the contents of the zip file, open the folder that matches your CircuitPython version, and copy the entire lib folder and the code.py file to your CIRCUITPY drive.

# SPDX-FileCopyrightText: 2021 ladyada for Adafruit Industries
# SPDX-License-Identifier: MIT

import time
import board
import busio
import adafruit_mcp9600

# frequency must be set for the MCP9600 to function.
# If you experience I/O errors, try changing the frequency.
i2c = busio.I2C(board.SCL, board.SDA, frequency=100000)
mcp = adafruit_mcp9600.MCP9600(i2c)

while True:
    print((mcp.ambient_temperature, mcp.temperature, mcp.delta_temperature))
    time.sleep(1)
The MCP9601 does not like zero-length writes directed to it, and will often not respond (it will NAK instead of ACK). This means it will often not respond to probes by `i2c.scan()` and similar scans of the I2C bus.
If you're running into other issues with your MCP9601 connecting to your non-SAMD microcontroller, consider changing the frequency to 20000 as a possible fix. SAMD-based microcontrollers MUST use 100kHz frequency or higher.

Ensure the following file and folder are in the lib folder on your CIRCUITPY drive:

  • adafruit_mcp9600.mpy
  • adafruit_bus_device/

Before continuing make sure your board's lib folder or root filesystem has the adafruit_mcp9600.mpy, and adafruit_bus_device files and folders copied over.

Next connect to the board's serial REPL so you are at the CircuitPython >>> prompt.

CircuitPython and Python Usage

To demonstrate the usage of the sensor we'll initialize it and read the temperature from the board's Python REPL.

Run the following code to import the necessary modules and initialize the I2C connection with the sensor. Note that frequency must be set when I2C is initialised for the MCP9601 to work:

import board
import busio
import adafruit_mcp9600

i2c = busio.I2C(board.SCL, board.SDA, frequency=100000)
mcp = adafruit_mcp9600.MCP9600(i2c)

If you find that your MCP9601 isn't connecting to your non-SAMD microcontroller (SAMD-based microcontrollers MUST use 100kHz frequency or higher!), consider changing the I2C initialisation to the following as a possible fix:

i2c = busio.I2C(board.SCL, board.SDA, frequency=20000)

 

Now that you've done imports and setup, you're ready to read values from the sensor using any of these properties:

  • temperature - The thermocouple or hot junction temperature in degrees Celsius.
  • ambient_temperature - The ambient or cold-junction temperature in degrees Celsius.
  • delta_temperature - The change in temperature.

Enter the following line of code into the REPL.

print(mcp.temperature)

An extended example is available under the CircuitPython Installation section. That's all there is to reading temperature using the MCP9601 and CircuitPython!

Alerts and More

The MCP9601 breakout allows you to configure four separate alerts on four pins. Connect the alert pins to digital output pins on your board or computer, and use the alert configuration in the MCP9600 library to configure them. Check out the documentation for more information!

This guide was first published on Aug 18, 2021. It was last updated on 2021-08-18 16:27:22 -0400.

This page (Python & CircuitPython) was last updated on Jun 30, 2022.

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