ROS2 RPi AS5048A Encoder Package

This package provides a ROS 2 node for interfacing with the AS5048A encoder via SPI on a Raspberry Pi. The node publishes encoder data to various ROS topics.

Tested on:

• Raspberry Pi 4B, Raspberry Pi CM4
• Ubuntu 22.04, ROS2 Humble

Features

• Reads data from the AS5048A encoder over SPI.
• Publishes raw angle and cumulative angle to ROS topics.

Dependencies

This package depends on several ROS 2 packages and the spidev Python package.

ROS 2 Dependencies

• rclpy
• std_msgs

Python Dependencies

• spidev

Installation

ROS 2 and Python Dependencies

1. Ensure ROS 2 is installed on your Raspberry Pi. You can follow the official ROS 2 installation guide.

2. Install ROS 2 Python dependencies:

   sudo apt update
   sudo apt install ros-humble-rclpy ros-humble-std-msgs 

3. Install spidev for Python:

   sudo apt install python3-pip
   sudo pip3 install spidev

Package Setup

1. Clone the repository into your ROS 2 workspace:

   cd ~/ros2_ws/src
   git clone https://github.com/atarbabgei/ros2_rpi_as5048a.git  

2. Build the package:

   cd ~/ros2_ws
   colcon build

3. Source the setup file to overlay the new package into your environment:

   source install/setup.bash

Hardware Connection

IMPORTANT: Power Supply Mode

Ensure that the AS5048A is running in 3.3V mode. Connecting the AS5048A to 5V mode may damage the Raspberry Pi. Verify the jumper settings or power connections on the AS5048A to make sure it operates at 3.3V.

Connect SPI0 between AS5048A and Raspberry Pi

AS5048A Pin	Raspberry Pi Pin
VCC	Pin 1 or Pin 17 (3.3V)
GND	Pin 6 (GND) or any other GND pin
MOSI	GPIO 10 (SPI0 MOSI)
MISO	GPIO 9 (SPI0 MISO)
SCK	GPIO 11 (SPI0 SCLK)
CS	GPIO 8 (SPI0 CE0)

Enable SPI on your Raspberry Pi

If using Ubuntu 22.04 OS, make sure SPI is enabled in config.txt:

dtparam=spi=on

Or if using Raspberry Pi OS:

sudo raspi-config

Navigate to Interfacing Options > SPI and enable it.

Usage

Run the node using the launch file:

ros2 launch ros2_rpi_as5048a encoder.launch.py

Node Details

Parameters

• encoder_resolution (float): The resolution of the AS5048A encoder.

Published Topics

• /encoder_absolute_angle (std_msgs/Float32): The absolute angle in radians (between 0 to $2\pi$).
• /encoder_cumulative_angle (std_msgs/Float32): The cumulative angle in radians.
• /encoder_angular_velocity (std_msgs/Float32): The angular velocity in rads/s.

License

MIT