Setting Up USB-to-UART Serial Communication with Raspberry Pi 5 and the Raspberry Pi Debug Probe

Efficient debugging and programming of Raspberry Pi devices is made seamless with the Raspberry Pi Debug Probe. This all-in-one USB-to-debug kit simplifies USB-to-UART communication, particularly for the Raspberry Pi 5, which has UART enabled by default. This blog post will guide you through the setup process for the Raspberry Pi 5 and briefly touch on configurations for the Raspberry Pi 4.

Overview of the Raspberry Pi Debug Probe

The Raspberry Pi Debug Probe provides a solderless and straightforward solution to connect your Raspberry Pi to a PC for serial communication. This is a Swiss army knife for embedded developers. The Raspberry Pi Debug Probe features a transparent plastic case and a green printed circuit board with microUSB connector and Raspberry Pi RP2040 microcontroller, the same chip used in Raspberry Pi Pico development board. Supporting USB-to-UART bridges and USB-to-two-wire serial debug bridges (including Arm Serial Wire Debug), it offers developers a powerful tool for debugging and programming.

For the Raspberry Pi 5, UART functionality is enabled out of the box, eliminating the need for manual configuration. This plug-and-play feature ensures that developers can focus on their projects without worrying about setup complexities.

Raspberry Pi 5: Built-In UART Support and Debug Connector

Raspberry Pi 5 introduces a dedicated UART connector, located between the two microHDMI connectors. This standardized, small, keyed, 3-pin connector supports both UART and 2-wire serial debug interfaces. Future Raspberry Pi devices with dedicated serial debug or UART interfaces will also adopt this specification where possible.

This 3-pin connector supports the following:

• UART Interface: Requires two unidirectional pins?one for transmitting data (TX) and another for receiving data (RX).
• 2-Wire Serial Debug Interfaces: Designed to work with a unidirectional clock pin and a bidirectional data I/O pin, supporting protocols like Arm?s Serial Wire Debug (SWD) or cJTAG.

The use of this standardized connector ensures compatibility across various debugging tools and simplifies the development process. Combined with the out-of-the-box UART support, Raspberry Pi 5 simplifies debugging, programming, and interacting with the device, making it ideal for developers and hobbyists seeking an efficient workflow.

For more detailed configuration guidance, refer to the Raspberry Pi configuration guide.

Raspberry Pi 4 and Older Models

For users working with the Raspberry Pi 4, enabling UART requires manual configuration:

• Modify config.txt: Add the line enable_uart=1 to the file located in the boot partition. Refer to the configuration guide for more details.
• Modify cmdline.txt: Append console=serial0,115200 to ensure kernel boot messages are output through the serial console.

These changes allow serial communication through GPIO pins 14 (TX) and 15 (RX), corresponding to pins 8 and 10 on the 40-pin header.

Connection Details

To establish USB-to-UART communication with the Raspberry Pi Debug Probe:

• Connect RX on the Raspberry Pi to TX on the Debug Probe.
• Connect TX on the Raspberry Pi to RX on the Debug Probe.
• Connect GND on both devices to complete the circuit.

Using Serial Communication Tools

Linux Distributions

On Linux systems, the screen command-line application is a straightforward tool for serial communication. For example:

sudo screen /dev/ttyACM0 115200

/dev/ttyACM0 is the device assigned to the Debug Probe.

115200 is the default baud rate for Raspberry Pi devices.

Use sudo to ensure superuser security privileges to access to the device.

Other Operating Systems

• macOS: The screen command is available by default.
• Windows: Tools like PuTTY or minicom (via WSL) can be used for serial communication.

ANAVI Infrared pHAT

For enthusiasts interested in expanding the functionality of their Raspberry Pi, the video accompanying this guide also showcases the ANAVI Infrared pHAT, an open-source hardware add-on board. This board provides infrared capabilities for the Raspberry Pi and is ideal for various automation projects.

You can learn more about the ANAVI Infrared pHAT and purchase it from the following retailers:

• Crowd Supply
• Mouser
• The Pi Hut
• Tindie
• Lectronz

For more details about ANAVI Infrared pHAT, visit ANAVI Technology.