This blog post details how to boot an RP2040-based Raspberry Pi Pico W (RP2350) directly from UART, bypassing the usual flash memory boot process. This is achieved by leveraging the ROM bootloader's capability to accept code over UART0. The post provides Python code to send a UF2 file containing a custom linker script and modified boot2 code directly to the Pico W via its UART interface. This custom boot2 then loads subsequent data from the UART, allowing the execution of code without relying on flashed firmware, useful for debugging and development purposes. The process involves setting specific GPIO pins for bootsel mode, utilizing the picotool utility, and establishing a 115200 baud UART connection.
This blog post details how to implement a simplified printf function for bare-metal environments, specifically ARM Cortex-M microcontrollers, without relying on a full operating system. The author walks through creating a minimal version that supports basic format specifiers like %c, %s, %u, %x, and %d, bypassing the complexities of a standard C library. The implementation utilizes a UART for output and includes a custom integer to string conversion function. By directly manipulating registers and memory, the post demonstrates a lightweight printf suitable for resource-constrained embedded systems.
HN commenters largely praised the article for its clear explanation of implementing printf in a bare-metal environment. Several appreciated the author's focus on simplicity and avoiding unnecessary complexity. Some discussed the tradeoffs between code size and performance, with suggestions for further optimization. One commenter pointed out the potential issues with the implementation's handling of floating-point numbers, particularly in embedded systems where floating-point support might not be available. Others offered alternative approaches, including using smaller, more specialized printf implementations or relying on semihosting for debugging. The overall sentiment was positive, with many finding the article educational and well-written.
Picoruby is a lightweight implementation of the Ruby programming language specifically designed for microcontrollers. Based on mruby/c, a minimal version of mruby, it aims to bring the flexibility and ease-of-use of a high-level language like Ruby to resource-constrained embedded systems. This allows developers to write more complex logic and algorithms on small devices using a familiar syntax, potentially simplifying development and improving code maintainability. The project includes a virtual machine, a garbage collector, and core Ruby classes, enabling a reasonable subset of Ruby functionality on microcontrollers.
HN users discussed the practicality and performance implications of using mruby and picoruby in resource-constrained environments. Some expressed skepticism about the actual performance benefits, questioning whether the overhead of the interpreter outweighs the advantages of using a higher-level language. Others highlighted the potential benefits for rapid prototyping and easier code maintenance. Several commenters pointed out that Lua is a strong competitor in this space, offering similar benefits with potentially better performance. The suitability of garbage collection for embedded systems was also debated, with concerns about unpredictable latency. Finally, some users shared their positive experiences using mruby in similar projects.
The blog post details the author's experience porting Rust to the RockPro64 (RP2350) single-board computer. They successfully brought up a minimal Rust environment, including core libraries, allowing basic "Hello, world!" functionality and interaction with GPIO pins. The process involved building a custom cross-compilation toolchain based on a pre-built Debian image, navigating architectural differences like the lack of an MMU, and implementing necessary drivers. While challenging, this achievement lays the groundwork for more complex Rust development on the RP2350, potentially opening doors for embedded systems applications.
HN commenters generally express enthusiasm for Rust's increasing viability on embedded platforms, particularly the RP2040. Several users discuss the benefits of Rust's memory safety and performance in this context, comparing it favorably to C/C++. Some point out the challenges of working with Rust on resource-constrained devices, like managing memory allocation and dealing with abstractions that can add overhead. A few commenters also mention specific crates like rp-pico and embassy, highlighting their usefulness for embedded Rust development on the RP2040. There's also discussion around build times, tooling, and the learning curve associated with Rust, with some suggesting that the ecosystem is still maturing but rapidly improving. Finally, some users share their own experiences and projects using Rust on embedded systems.
The blog post "ESP32 WiFi Superstitions" explores common practices developers employ when troubleshooting ESP32 WiFi connectivity issues, despite lacking a clear technical basis. The author argues that many of these "superstitions," like adding delays, calling WiFi.begin() repeatedly, or disabling power-saving modes, often mask underlying problems with poor antenna design, inadequate power supply, or incorrect configuration rather than addressing the root cause. While these tweaks might sometimes appear to improve stability, they are ultimately unreliable solutions. The post encourages a more systematic debugging approach focusing on identifying and resolving the actual hardware or software issues causing the instability.
Hacker News users generally agreed with the author's point about the ESP32's WiFi sensitivity, sharing their own struggles and workarounds. Several commenters emphasized the importance of antenna design and placement, suggesting specific antenna types and advocating for proper grounding. Others pointed out the impact of environmental factors like metal enclosures and nearby electronics. The discussion also touched on potential firmware issues and the value of using a logic analyzer for debugging. Some users shared specific success stories by adjusting antenna placement or implementing suggested fixes. One commenter highlighted the challenges of reliable WiFi in battery-powered devices due to the power-hungry nature of WiFi, while another speculated on potential hardware limitations of the ESP32's radio circuitry.
This project showcases WiFi-controlled RC cars built using ESP32 microcontrollers. The cars utilize readily available components like a generic RC car chassis, an ESP32 development board, and a motor driver. The provided code establishes a web server on the ESP32, allowing control through a simple web interface accessible from any device on the same network. The project aims for simplicity and ease of replication, offering a straightforward way to experiment with building your own connected RC car.
Several Hacker News commenters express enthusiasm for the project, praising its simplicity and the clear documentation. Some discuss potential improvements, like adding features such as obstacle avoidance or autonomous driving using a camera. Others share their own experiences with similar projects, mentioning alternative chassis options or different microcontrollers. A few users suggest using a more robust communication protocol than UDP, highlighting potential issues with range and reliability. The overall sentiment is positive, with many commenters appreciating the project's educational value and potential for fun.
This blog post details how to leverage the Rust standard library (std) within applications running on the NuttX Real-Time Operating System (RTOS), a common choice for embedded systems. The author demonstrates a method to link the Rust std components, specifically write() for console output, with NuttX's system calls. This allows developers to write Rust code that feels idiomatic, using familiar functions like println!(), while still targeting the resource-constrained environment of NuttX. The process involves creating a custom target specification JSON file and implementing shim functions that bridge the gap between the Rust standard library's expectations and the underlying NuttX syscalls. The result is a simplified development experience, enabling more portable and maintainable Rust code on embedded platforms.
Hacker News users discuss the challenges and advantages of using Rust with NuttX. Some express skepticism about the real-world practicality and performance benefits, particularly regarding memory usage and the overhead of Rust's safety features in embedded systems. Others highlight the potential for improved reliability and security that Rust offers, contrasting it with the inherent risks of C in such environments. The complexities of integrating Rust's memory management with NuttX's existing mechanisms are also debated, along with the potential need for careful optimization and configuration to realize Rust's benefits in resource-constrained systems. Several commenters point out that while intriguing, the project is still experimental and requires more maturation before becoming a viable option for production-level embedded development. Finally, the difficulty of porting existing NuttX drivers to Rust and the lack of a robust Rust ecosystem for embedded development are identified as potential roadblocks.
The openai-realtime-embedded-sdk allows developers to build AI assistants that run directly on microcontrollers. This SDK bridges the gap between OpenAI's powerful language models and resource-constrained embedded devices, enabling on-device inference without relying on cloud connectivity or constant internet access. It achieves this through quantization and compression techniques that shrink model size, allowing them to fit and execute on microcontrollers. This opens up possibilities for creating intelligent devices with enhanced privacy, lower latency, and offline functionality.
Hacker News users discussed the practicality and limitations of running large language models (LLMs) on microcontrollers. Several commenters pointed out the significant resource constraints, questioning the feasibility given the size of current LLMs and the limited memory and processing power of microcontrollers. Some suggested potential use cases where smaller, specialized models might be viable, such as keyword spotting or limited voice control. Others expressed skepticism, arguing that the overhead, even with quantization and compression, would be too high. The discussion also touched upon alternative approaches like using microcontrollers as interfaces to cloud-based LLMs and the potential for future hardware advancements to bridge the gap. A few users also inquired about the specific models supported and the level of performance achievable on different microcontroller platforms.
Summary of Comments ( 20 )
https://news.ycombinator.com/item?id=43954054
Hacker News users discuss various aspects of booting the RP2350 from UART. Several commenters appreciate the detailed blog post, finding it helpful and well-written. Some discuss alternative approaches like using a Raspberry Pi Pico as a USB-to-serial adapter or leveraging the RP2040's ROM bootloader. A few highlight the challenges of working with UART, including baud rate detection and potential instability. Others delve into the technical details, mentioning the RP2040's USB boot mode and comparing it to other microcontrollers. The overall sentiment is positive, with many praising the author for sharing their knowledge and experience.
The Hacker News post "Booting the RP2350 from UART" (https://news.ycombinator.com/item?id=43954054) has a modest number of comments, sparking a discussion around the intricacies of the RP2040's boot process and the implications of UART booting.
One commenter highlights the usefulness of UART booting for situations where the flash chip is corrupted, allowing for recovery and reprogramming. They express appreciation for the detailed blog post, emphasizing the value of understanding the low-level workings of the microcontroller.
Another commenter focuses on the wider context of microcontroller security, pointing out the potential vulnerabilities introduced by an exposed UART boot mode. They argue that if an attacker gains physical access, they could potentially compromise the device. This comment sparks a brief discussion about the balance between convenient debugging/recovery features and the security risks they entail, with suggestions for mitigating these risks through hardware or software mechanisms.
Another participant dives deeper into the technical aspects of the RP2040's boot ROM, explaining how it checks for specific conditions on the GPIO pins to determine the boot mode. They appreciate the author's clarification on the boot process, noting it corrected their own misunderstanding.
One comment thread delves into the complexities of different boot modes and their respective advantages. Specifically, they discuss the trade-offs between using a dedicated boot pin versus relying on existing GPIOs, considering factors like pin availability and potential conflicts with other functionalities. This discussion also touches on the broader topic of designing robust and flexible bootloaders.
Finally, a commenter reflects on their own experience with the RP2040, expressing frustration with the lack of clear documentation regarding the boot process. They commend the blog post author for providing valuable insights and filling this documentation gap. This sentiment echoes the general appreciation for the article's clarity and depth in explaining a complex technical process.