Finding a New ESP32 Port - A Step-by-Step Guide

Published on September 27, 2025, by Mike | MikesBlogDesign

Introduction

Working with multiple ESP32 boards can sometimes lead to port confusion, especially when uploading sketches via the Arduino IDE on Mac OS X. Recently, I encountered an error indicating the serial port /dev/cu.usbserial-1140 was unavailable, suggesting a change in port assignment. This guide will walk you through finding the new port for your second ESP32, ensuring smooth uploads and development.

Steps to Find the New Port

Check Physical Connection

Ensure your second ESP32 is securely connected via USB. Try a different cable or USB port on your Mac if the current setup fails.
Open Arduino IDE

Launch Arduino IDE (version 1.8.19 in this case) to access port management tools.
Access the Port Menu

Navigate to Tools > Port. Available ports, such as /dev/cu.usbserial-XXXX, will be listed for USB-to-serial devices.
Identify the New Port

Disconnect the first ESP32, note the ports, then connect the second ESP32. The new port (e.g., /dev/cu.usbserial-1150) that appears is likely your target.
Select the Port

Choose the new port from the Tools > Port menu and confirm the board is set to ESP32 Dev Module under Tools > Board.
Test Compilation and Upload

Click the Upload button. If the port is correct, the sketch should upload successfully.

Additional Troubleshooting

Port Busy: If the port is listed but busy, close other apps (e.g., Terminal, another IDE instance). Use Terminal to check:

lsof | grep /dev/cu.usbserial-1140

Kill the process with: kill -9 <PID>

USB Driver Issue

Verify the CH340/CH341 or CP210x driver is installed for your ESP32’s USB chip. Download from the manufacturer if needed.
Reset the Board

Press the reset button or power cycle the ESP32 to ensure it’s in upload mode.
Verbose Output

Enable Show verbose output during compilation in File > Preferences for detailed logs.

Conclusion

With the new port identified and selected, your second ESP32 should be ready for development. This process ensures seamless integration into projects like my ESP32 Bitcoin price display. Stay tuned for more tech tips on MikesBlogDesign!