Raspberry Pi Pico: A Versatile yet Underwhelming Ethernet Experience

The Raspberry Pi Pico, a recent addition to the popular Raspberry Pi series, has been making waves in the maker community with its impressive capabilities and compact design. However, when it comes to networking, the board's implementation of bit-banged 100 MBit/s Fast Ethernet is still a surprise, even for those familiar with the world of microcontrollers.

In this article, we'll delve into the details of the Raspberry Pi Pico's Ethernet capabilities, explore the limitations of its implementation, and discuss potential workarounds. We'll also examine the impact of these findings on the overall design and development process of projects utilizing the Raspberry Pi Pico.

The Raspberry Pi Pico: A Brief Overview

For those who may be unfamiliar with the Raspberry Pi Pico, it's essential to understand its background. The Raspberry Pi Foundation, a UK-based charity organization, designed the Pico as an affordable, credit-card-sized microcontroller board based on the RP2040 (or RP2350) chip. This system-on-chip features two ARM Cortex-M0+ CPUs, 264KB of RAM, and a plethora of I/O pins.

Released in May 2021, the Raspberry Pi Pico has been gaining traction among makers, hobbyists, and developers due to its low cost, ease of use, and versatility. With the Pico, users can create a wide range of projects, from simple IoT devices to complex robotics systems.

The Ethernet Conundrum

When it comes to networking, one might expect the Raspberry Pi Pico to offer more robust connectivity options. However, its implementation of bit-banged 100 MBit/s Fast Ethernet is surprisingly limited. This limitation stems from the RP2040's (or RP2350's) hardware capabilities.

The RP2040 features a single MII (Media Interface Unit) for Gigabit Ethernet, which can only support speeds up to 1 Gbps. While this may seem sufficient for many applications, the Pico's implementation of bit-banging over the RPi header (which uses SPI communication) is still a surprise.

The Pico-100BASE-TX Library

In an effort to address this limitation, Steve, a member of the Raspberry Pi community, has developed the Pico-100BASE-TX library. This library allows users to utilize the RP2040's (or RP2350's) hardware capabilities to implement 100 MBit/s Fast Ethernet.

The Pico-100BASE-TX library uses bit-banging to communicate with the RPi header, exploiting its SPI interface to transmit data over the Ethernet connection. While this implementation may not be as elegant or efficient as other networking solutions, it demonstrates the community's willingness to work around the limitations of the RP2040.

Limitations and Potential Workarounds

While the Pico-100BASE-TX library is a great example of community-driven innovation, its implementation has some significant limitations:

• Throughput: The bit-banging approach used in the Pico-100BASE-TX library may not be as efficient as other networking solutions, potentially leading to reduced throughput and increased latency.
• Interfacing with RPi Header: Using the SPI interface to communicate with the RPi header can be prone to errors and may require additional hardware modifications.

To overcome these limitations, users can consider alternative networking solutions, such as:

• USB-Based Ethernet Adapters: Users can connect a USB-based Ethernet adapter to the Raspberry Pi Pico, which would provide more robust and efficient networking capabilities.
• Alternative Networking Libraries: Researchers and developers may be able to create alternative networking libraries that exploit the RP2040's (or RP2350's) hardware capabilities in more efficient ways.

Impact on Design and Development

The limitations of the Raspberry Pi Pico's Ethernet implementation have significant implications for design and development:

• Project Planning: When working with the Raspberry Pi Pico, users must carefully consider their networking requirements and plan accordingly.
• Component Selection: Users may need to choose alternative components or solutions to achieve their desired networking performance.

In conclusion, while the Raspberry Pi Pico's Ethernet implementation is not ideal, it highlights the importance of community-driven innovation and out-of-the-box thinking. By understanding the limitations and potential workarounds, users can plan and design projects that effectively utilize this versatile microcontroller board.

Conclusion

The Raspberry Pi Pico is a powerful tool for makers and developers, but its Ethernet implementation has some surprising limitations. While the Pico-100BASE-TX library provides a viable solution, it's essential to understand these limitations and plan accordingly. By embracing community-driven innovation and exploring alternative networking solutions, users can create innovative projects that effectively utilize this compact microcontroller board.

Future Developments

As research and development continue for the Raspberry Pi Pico, we can expect to see:

• Improved Networking Capabilities: The RP2040 (or RP2350) chip may be updated with new features or improved performance.
• Alternative Solutions: Alternative networking libraries or solutions may emerge, providing more efficient and robust connectivity options.

Stay tuned for further updates on the Raspberry Pi Pico's development and its potential impact on maker communities worldwide.