Adafruit ICM-20948 User Manual

Adafruit TDK InvenSense ICM-20948 9-DoF IMU

Created by Bryan Siepert

Last updated on 2020-08-05 06:29:22 PM EDT

Overview

When you want to sense orientation using inertial measurements, you need an Inertial Measurement Unit, and when it

comes to IMUs, the more DoFs, the better! The ICM20948 from Invensense packs 9 Degrees of freedom into a teeny

package, making it a one stop shop for all the DOFs you need! Within it’s svelte 3x3mm package there are not just

one

MEMS sensor die like your common sensors, but

two sensor dies!

The ICM20948 pair’s Invensense’s MEMS 3-axis

accelerometer and gyro with the AK09916 3-axis magnetometer from Asahi Kasei Microdevices Corporation.

All 9 axes of measurement are made available thanks to a crew of 16-bit Analog to Digital Converters, diligently

converting the raw analog signals from the MEMs sensors to digital readings that are accessed via I2C or SPI. Each of

the sensors have the quality specs you would expect from such a sensor. Just see what the datasheet has to say:

• 3-Axis Gyroscope with Programmable FSR of ±250 dps, ±500 dps, ±1000 dps, and ±2000 dps

• 3-Axis Accelerometer with Programmable FSR of ±2g, ±4g, ±8g, and ±16g

• 3-Axis Compass with a wide range to ±4900 µT

Now that’s a handy and capable team of sensors, ready to help orient your project in the right direction!

Like any high performance device the ICM20948 can a bit particular about how it needs to be worked with. Unlike the

pick and place machines that normally handle these sensors, most of us humans can’t readily take a little guy like the

ICM20948 and plop it into our circuit; it’s small! What’s more, the ICM20948 runs on 1.8V which is increasingly common

for device manufacturers but isn’t hardly common for makers, learners, prototypers or the like. With that in mind, we’ve

put the ICM20948 on a breakout with a 1.8V voltage regulator as well as level shifting circuitry to allow your 3.3V

device such as a Feather M4 or Raspberry Pi, or a 5V device such as the Arduino Uno.

To make connections easy, our breakout puts makes the pins of the ICM20948 available on standard 0.100”/ 2.54mm

pitch headers for use with a breadboard. Should you wish to avoid soldering, the Stemma QT form factor breakout also includes our Stemma QT connectors which just like the SparkFun Qwiic (https://adafru.it/Fpw) connectors they’re

inspired by (and compatible with). Using these handy connectors you can simply plug in the sensor and get rolling with

your project. You can even use them to daisy chain multiple sensors together! All of this is explained with wiring

diagrams for use with Arduino or CircuitPython on the pages to come.

Lastly, all the wiring in the world wouldn’t do you much good if you didn’t know how to use those wires to talk to your

sensor, so we’ve done the work of writing libraries for Arduino and CircuitPython that will allow you to use the

ICM20948 with your favorite development board, be it an Arduino, Feather, Raspberry Pi, or one of the many other

Arduino and CircuitPython compatible boards.

Pinouts

Power Pins

VIN - this is the power pin. Since the sensor chip uses 3 VDC, we have included a voltage regulator on board that

will take 3-5VDC and safely convert it down. To power the board, give it the same power as the logic level of

your microcontroller - e.g. for a 5V microcontroller like Arduino, use 5V

1V8 - this is the 1.8V output from the voltage regulator, you can grab up to 100mA from this if you like GND - common ground for power and logic

I2C Logic Pins

SCL - I2C clock pin, connect to your microcontroller I2C clock line. This pin is level shifted so you can use 3-5V logic, and there's a 10K pullup on this pin. SDA - I2C data pin, connect to your microcontroller I2C data line. This pin is level shifted so you can use 3-5V logic, and there's a 10K pullup on this pin.

STEMMA QT (https://adafru.it/Ft4) - These connectors allow you to connectors to dev boards with STEMMA QT

connectors or to other things with various associated accessories (https://adafru.it/Ft6) SDO/ADR Jumper - I2C Address pin. Pulling this pin high or bridging the solder jumper on the back will change the I2C address from 0x69 to 0x68

SPI Logic pins

SCL - This is

also

the SPI Clock pin / SCK, it's an input to the chip

SDA - this is

also

the Serial Data In / Microcontroller Out Sensor In / MOSI pin, for data sent from your processor

to the ICM20948 SDO - this is the Serial Data Out / Microcontroller In Sensor Out / MISO pin, for data sent from the ICM20948 to

your processor. CS - this is the Chip Select pin, drop it low to start an SPI transaction. It's an input to the chip

If you want to connect multiple ICM20948s to one microcontroller, have them share the SCL, SDA, and DO pins. Then assign each one a unique CS pin.

Other Pins

INT -This is the primary interrupt pin. You can setup the ICM20948 to pull this low or high when certain

conditions are met such as new measurement data being available. Consult the datasheet (https://adafru.it/Iqf) for

usage AC - Auxillary I2C bus clock. Advanced users can consult the datasheet (https://adafru.it/MC5) to learn how to use this pin to communicate with sensors on the ICM20948's auxillary bus. 1.8V Logic Only! AD - Auxillary I2C bus data. Advanced users can consult the datasheet (https://adafru.it/MC5) to learn how to use this pin to communicate with sensors on the ICM20948's auxillary bus. 1.8V Logic Only! FS - External frame sync. Advanced users can consult the datasheet (https://adafru.it/MC5) to learn how to use this pin to synchronize measurements with additional sensors. 1.8V Logic Only!

Arduino

Using the ICM20948 with Arduino is a simple matter of wiring up the sensor to your Arduino-compatible

microcontroller, installing the Adafruit ICM20X (https://adafru.it/MC6) library we've written, and running the provided

example code.

I2C Wiring

Use this wiring if you want to connect via I2C interface. The default I2C address for the ICM20948 is 0x69 but it can be switched to 0x68 by pulling the address pin low to GND.

Here is how to wire up the sensor using one of the STEMMA QT (https://adafru.it/Ft4) connectors. The examples show

a Metro but wiring will work the same for an Arduino or other compatible board.

Connect board VIN (red wire) to Arduino 5V if you

are running a 5V board Arduino (Uno, etc.). If your

board is 3V, connect to that instead.

Connect board GND (black wire) to Arduino GND

Connect board SCL (yellow wire) to Arduino SCL

Connect board SDA (blue wire) to Arduino SDA

Here is how to wire the sensor to a board using a solderless breadboard:

Connect board VIN (red wire) to Arduino 5V if you

are running a 5V board Arduino (Uno, etc.). If your

board is 3V, connect to that instead.

Connect board GND (black wire) to Arduino GND

Connect board SCL (yellow wire) to Arduino SCL

Connect board SDA (blue wire) to Arduino SDA

Library Installation

You can install the Adafruit ICM20X library for Arduino using the Library Manager in the Arduino IDE. This library is

compatible with both the ICM20948 and it's sister sensor, the ICM20649

Click the Manage Libraries ... menu item, search for Adafruit ICM20X, and select the Adafruit ICM20X library:

Follow the same process for the Adafruit BusIO library.

Finally follow the same process for the Adafruit Unified Sensor library:

Load Example

Open up File -> Examples -> Adafruit ICM20X -> adafruit_ICM20948_test

After opening the demo file, upload to your Arduino wired up to the sensor. Once you upload the code, you will see the Temperature as well as X, Y, and Z values for the Gyro Accelerometer, and Magnetometer being printed when you open the Serial Monitor (Tools->Serial Monitor) at 115200 baud, similar to this:

Example Code

Temporarily unable to load content:

Arduino Docs

Arduino Docs (https://adafru.it/MC0)

Python & CircuitPython

It's easy to use the ICM20948 with Python and CircuitPython, and the Adafruit CircuitPython

ICM20X (https://adafru.it/LAp) module. This module allows you to easily write Python code that reads measurements

from the accelerometer and gyro, and will work with either 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 (https://adafru.it/BSN).

CircuitPython Microcontroller Wiring

First wire up a ICM20948 to your board exactly as shown below. Here's an example of wiring a Feather M4 to the sensor with I2C using one of the handy STEMMA QT (https://adafru.it/Ft4) connectors:

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)

You can also use the standard 0.100" pitch headers to wire it up on a breadboard:

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 (https://adafru.it/BSN).

Here's the Raspberry Pi wired to the sensor using I2C and a STEMMA QT (https://adafru.it/Ft4) connector:

Pi 3V to sensor VCC (red wire)

Pi GND to sensor GND (black

wire)

Pi SCL to sensor SCL (yellow wire)

Pi SDA to sensor SDA (blue wire)

Finally here is an example of how to wire up a Raspberry Pi to the sensor using a solderless breadboard

Pi 3V to sensor VCC (red wire)

Pi GND to sensor GND (black

wire)

Pi SCL to sensor SCL (yellow wire)

Pi SDA to sensor SDA (blue wire)

CircuitPython Installation of ICM20X Library

You'll need to install the Adafruit CircuitPython ICM20X (https://adafru.it/LAp) library on your CircuitPython board.

First make sure you are running the latest version of Adafruit CircuitPython (https://adafru.it/Amd) for your board.

Next you'll need to install the necessary libraries to use the hardware--carefully follow the steps to find and install these

libraries from Adafruit's CircuitPython library bundle (https://adafru.it/ENC). Our CircuitPython starter guide has a great

page on how to install the library bundle (https://adafru.it/ABU).

For non-express boards like the Trinket M0 or Gemma M0, you'll need to manually install the necessary libraries from

the bundle:

adafruit_icm20X.mpy adafruit_bus_device adafruit_register

Before continuing make sure your board's lib folder has the adafruit_icm20X.mpy, adafruit_bus_device, and adafruit_register files and folders copied over.

Next connect to the board's serial REPL (https://adafru.it/Awz)so you are at the CircuitPython >>> prompt.

Python Installation of ICM20X 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 (https://adafru.it/BSN)!

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

sudo pip3 install adafruit-circuitpython-icm20x

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 & Python Usage

To demonstrate the usage of the sensor we'll initialize it and read the temperature and humidity measurements from

the board's Python REPL.

Run the following code to import the necessary modules and initialize the I2C connection with the sensor:

Now you're ready to read values from the sensor using these properties:

acceleration - The acceleration forces in the X, Y, and Z axes in m/s gyro - The rotation measurement on the X, Y, and Z axes in degrees/sec magnetic - The magnetic forces on the X, Y, and Z axes in micro-Teslas (uT)

For example, to print out the acceleration, gyro and magnetic measurements use this code:

Example Code

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2

Python Docs

Python Docs (https://adafru.it/MC1)

Downloads

Files

ICM20948 Datasheet (https://adafru.it/MC5)

EagleCAD files on GitHub (https://adafru.it/MC7)

Fritzing object in the Adafruit Fritzing Library (https://adafru.it/MC8)

Schematic

Fab Print

Adafruit ICM-20948 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual