icm20x_imu

Library for using the icm20x Imu, specifically the icm20948

Installation

These steps should allow you to completely install and run an icm20948 thoruhg a usb to ft232h connection

Devices needed

• FT232H chip with jst and usb c connectors
• Jst 4-pin cable
• USB A to USB C cable
• Icm20948 9-dof imu

Connect the ft232h to the icm20948 using the jst cable. Then connect the usb c to the ft232h, and plug in to the desired system via USB A

Note: if the Ft232h chip is a newer version with a small switch at the top that says 'i2c mode', make sure it is switched to 'on'

Install Prerequisites

These intaillation instructions are modified from here.

Tested with python3 and ROS (Tested with ROS Noetic)

Install libusb

sudo apt-get install libusb-1.0-0-dev

Setup udev rules

Add the following to etc/udev/rules.d/11-ftdi.rules

# /etc/udev/rules.d/11-ftdi.rules
SUBSYSTEM=="usb", ATTR{idVendor}=="0403", ATTR{idProduct}=="6001", GROUP="plugdev", MODE="0666"
SUBSYSTEM=="usb", ATTR{idVendor}=="0403", ATTR{idProduct}=="6011", GROUP="plugdev", MODE="0666"
SUBSYSTEM=="usb", ATTR{idVendor}=="0403", ATTR{idProduct}=="6010", GROUP="plugdev", MODE="0666"
SUBSYSTEM=="usb", ATTR{idVendor}=="0403", ATTR{idProduct}=="6014", GROUP="plugdev", MODE="0666"
SUBSYSTEM=="usb", ATTR{idVendor}=="0403", ATTR{idProduct}=="6015", GROUP="plugdev", MODE="0666"

Install pyftdi

The pyftdi library has been changed to decrease latency and need to be installed from source. The original code can be found here.

git clone [email protected]:AutonomousFieldRoboticsLab/pyftdi.git
cd pyftdi
pip  install .

Install Adafruit-Blinka

pip install Adafruit-Blinka

Install the icm20x library The original library is located here. This library has been changed to remove some sleep commands.

git clone [email protected]:AutonomousFieldRoboticsLab/Adafruit_CircuitPython_ICM20X.git
cd Adafruit_CircuitPython_ICM20X
pip install .

There are scripts inside examples folder to test icm20948 connection. You can test them.

Installation

mkdir -p ~/catkin_ws/src
cd ~/catkin_ws/src
git clone https://github.com/AutonomousFieldRoboticsLab/icm20x_imu
cd ~/catkin_ws
catkin_make

Usage

cd ~/catkin_ws
source devel/setup.bash
roslaunch icm20x_imu imu_node.launch 

Note The imu rate is set to 80. The magentic field rate is set to 20Hz (imu rate / 4). The speed could not be increased more than this.

• Decreasing the latency in the pyftdi library to 1ms results in abrupt connection loss.