micro-ROS Setup (ROS 2 Humble)

This guide covers micro-ROS setup on a ROS 2 Humble PC and sensor code for an ESP32.

Hardware requirements

ESP32 development board
MPU6050 IMU sensor (I2C)
Digital IR sensor
Rotary encoder
Connecting wires

Code files

Download the files in this guide. The Arduino sketch uses placeholder WiFi credentials; add your own locally before uploading.

Wiring connections

MPU6050 (I2C)

VCC → 3.3V
GND → GND
SDA → GPIO 21 (default I2C SDA)
SCL → GPIO 22 (default I2C SCL)

IR sensor

VCC → 3.3V or 5V (depending on sensor)
GND → GND
OUT → GPIO 25

Rotary encoder

VCC → 3.3V
GND → GND
CLK (A) → GPIO 26
DT (B) → GPIO 27

PC setup (ROS 2 Humble)

Step 1: Run the setup script

From the directory where you saved the script:

chmod +x setup_microros_workspace_humble.sh
./setup_microros_workspace_humble.sh

Step 2: Start the micro-ROS agent

Open a terminal and run:

cd ~/microros_ws
source install/local_setup.bash
ros2 run micro_ros_agent micro_ros_agent udp4 --port 8888

Keep this terminal running while the ESP32 is operating.

Arduino setup (ESP32)

Step 1: Install Arduino IDE

Download Arduino IDE from arduino.cc.

Step 2: Install ESP32 board support

Open Arduino IDE.
Go to File → Preferences.
Add this URL to Additional Board Manager URLs:

https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json

Go to Tools → Board → Boards Manager.
Search for esp32 and install ESP32 by Espressif Systems.

Step 3: Install required libraries

In Tools → Manage Libraries, install:

micro_ros_arduino — search for micro_ros_arduino and install the latest version.
MPU6050 by Electronic Cats.
I2Cdevlib, if the dependency was not installed automatically.

Step 4: Configure the code

Open microros_esp32_sensors_humble.ino and set:

WiFi credentials — replace YOUR_WIFI_SSID and YOUR_WIFI_PASSWORD locally.
ROS 2 agent IP — replace the sample address with your PC’s LAN IP. On Linux, the original notes use:
```
ip addr show | grep inet
```

Pin definitions — adjust the IR and encoder pins if your wiring differs:

#define IR_SENSOR_PIN 25
#define ENCODER_PIN_A 26
#define ENCODER_PIN_B 27

Step 5: Upload to ESP32

Connect the ESP32 over USB.
Select Tools → Board → ESP32 Arduino → ESP32 Dev Module (or your specific board).
Select the ESP32 under Tools → Port.
Click Upload.

Testing

Step 1: Monitor serial output

Open Serial Monitor at 115200 baud and check the MPU6050, WiFi, and micro-ROS initialization messages.

Step 2: Verify ROS 2 topics

In a new terminal:

source /opt/ros/humble/setup.bash
ros2 topic list

The sketch publishes:

/imu/data
/ir_sensor/data
/encoder/position

Step 3: View sensor data

ros2 topic echo /imu/data
ros2 topic echo /ir_sensor/data
ros2 topic echo /encoder/position

Troubleshooting

ESP32 won’t connect to WiFi

Double-check the SSID and password.
Ensure the network is 2.4 GHz; ESP32 does not support 5 GHz WiFi.
Check WiFi signal strength.

micro-ROS connection fails

Verify the PC IP address.
Ensure the micro-ROS agent is running.
Check firewall settings and allow UDP port 8888.
Ensure the ESP32 and PC are on the same network.

MPU6050 is not detected

Check the I2C wiring (SDA and SCL).
Try swapping SDA and SCL if it is still not detected.
Verify the 3.3V supply.

Encoder does not count

Check pull-up resistors; the code enables internal pull-ups.
Verify GPIO 26 and GPIO 27 wiring.
Test the encoder by rotating it.

No topics are visible in ROS 2

Ensure the micro-ROS agent is running.
Check the ESP32 serial output for errors.
Verify network connectivity.
Restart the agent and the ESP32.

Publishing rate

The code publishes all sensor data at 100 Hz (every 10 ms). Change timer_timeout in the sketch to change the interval:

const unsigned int timer_timeout = 10;  // milliseconds

Additional notes

IMU data is converted to standard ROS units: m/s² for acceleration and rad/s for angular velocity.
The encoder tracks relative position (positive or negative).
The IR sensor returns true/false (HIGH/LOW).
All topics publish simultaneously at the same rate.

Next steps

Create a ROS 2 node to process the sensor data.
Record data with ros2 bag record.
Visualize IMU data in RViz2.
Build robot-control systems using this sensor feedback.

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