Introduction¶

The MCP9808 is an awesome, high accuracy temperature sensor that communicates over I2C. Its available on Adafruit as a breakout.

Dependencies¶

This driver depends on:

Please ensure all dependencies are available on the CircuitPython filesystem. This is easily achieved by downloading the Adafruit library and driver bundle.

Installing from PyPI¶

On supported GNU/Linux systems like the Raspberry Pi, you can install the driver locally from PyPI. To install for current user:

pip3 install adafruit-circuitpython-mcp9808

To install system-wide (this may be required in some cases):

sudo pip3 install adafruit-circuitpython-mcp9808

To install in a virtual environment in your current project:

mkdir project-name && cd project-name
python3 -m venv .env
source .env/bin/activate
pip3 install adafruit-circuitpython-mcp9808

Usage Notes¶

Getting the temperature in Celsius is easy! First, import all of the pins from the board, board.I2C() for native I2C communication and the thermometer library itself.

import board
import adafruit_mcp9808

Next, initialize the I2C bus in a with statement so it always gets shut down ok. Then, construct the thermometer class:

# Do one reading
with i2c = board.I2C() as i2c:
    t = adafruit_mcp9808.MCP9808(i2c)

    # Finally, read the temperature property and print it out
    print(t.temperature)

Contributing¶

Contributions are welcome! Please read our Code of Conduct before contributing to help this project stay welcoming.

Documentation¶

For information on building library documentation, please check out this guide.

Table of Contents¶

Simple test¶

Ensure your device works with this simple test.

examples/mcp9808_simpletest.py¶

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

import time
import board
import adafruit_mcp9808

i2c = board.I2C()  # uses board.SCL and board.SDA

# To initialise using the default address:
mcp = adafruit_mcp9808.MCP9808(i2c)

# To initialise using a specified address:
# Necessary when, for example, connecting A0 to VDD to make address=0x19
# mcp = adafruit_mcp9808.MCP9808(i2c_bus, address=0x19)

while True:
    tempC = mcp.temperature
    tempF = tempC * 9 / 5 + 32
    print("Temperature: {} C {} F ".format(tempC, tempF))
    time.sleep(2)

Temperature Limit test¶

Show the MCP9808 to setup different temperature values

examples/mcp9808_temperature_limits.py¶

# SPDX-FileCopyrightText: 2021 Jose David M.
# SPDX-License-Identifier: MIT

"""
Show the MCP9808 to setup different temperature values
"""

import time
import board
import adafruit_mcp9808

i2c = board.I2C()  # uses board.SCL and board.SDA
mcp = adafruit_mcp9808.MCP9808(i2c)

# Change the values according to the desired values
print("Setting Temperature Limits")
mcp.upper_temperature = 23
mcp.lower_temperature = 10
mcp.critical_temperature = 100

# To verify the limits we need to read the temperature value
print(mcp.temperature)
time.sleep(0.3)  # This is the time temperature conversion at maximum resolution

# Showing temperature Limits
while True:
    if mcp.below_lt:
        print("too cold!")
    if mcp.above_ut:
        print("getting hot!")
    if mcp.above_ct:
        print("Above critical temp!")

`adafruit_mcp9808`¶

CircuitPython library to support MCP9808 high accuracy temperature sensor.

Author(s): Scott Shawcroft, Jose David M.

Implementation Notes¶

Hardware:

Adafruit MCP9808 High Accuracy I2C Temperature Sensor Breakout (Product ID: 1782)

Software and Dependencies:

Adafruit CircuitPython firmware for the supported boards: https://github.com/adafruit/circuitpython/releases
Adafruit’s Bus Device library: https://github.com/adafruit/Adafruit_CircuitPython_BusDevice
Adafruit’s Register library: https://github.com/adafruit/Adafruit_CircuitPython_Register

Notes:

Datasheet: http://www.adafruit.com/datasheets/MCP9808.pdf

class adafruit_mcp9808.MCP9808(i2c_bus, address=24)[source]¶

Interface to the MCP9808 temperature sensor.

Parameters:	i2c_bus (I2C) – The I2C bus the MCP9808 is connected to. address (int) – The I2C address of the device. Defaults to `0x18`

MCP9808 Settings

You could set the MCP9808 with different temperature limits and compare them with the ambient temperature Ta

above_ct this value will be set to True when Ta is above this limit
above_ut: this value will be set to True when Ta is above this limit
below_lt: this value will be set to True when Ta is below this limit

To get this value, you will need to read the temperature, and then access the attribute

Quickstart: Importing and using the MCP9808

Here is an example of using the MCP9808 class. First you will need to import the libraries to use the sensor
import board
import adafruit_mcp9808
Once this is done you can define your board.I2C object and define your sensor object
i2c = board.I2C()   # uses board.SCL and board.SDA
mcp = adafruit_mcp9808.MCP9808(i2c_bus)
Now you have access to the change in temperature using the temperature attribute. This temperature is in Celsius.
temperature = mcp.temperature

above_critical¶: True when the temperature is above the currently set critical temperature. False Otherwise

above_upper¶: True when the temperature is above the currently set high temperature. False Otherwise

below_lower¶: True when the temperature is below the currently set lower temperature. False Otherwise

critical_temperature¶: Critical alarm temperature in Celsius

lower_temperature¶: Lower alarm temperature in Celsius

resolution¶

Temperature Resolution in Celsius

Value	Resolution	Reading Time
0	0.5°C	30 ms
1	0.25°C	65 ms
2	0.125°C	130 ms
3	0.0625°C	250 ms

temperature¶: Temperature in Celsius. Read-only.

upper_temperature¶: Upper alarm temperature in Celsius