This post details how to access the Qualcomm Quectel BG96 modem embedded within the RAK5010 WisBlock Core module via USB. The BG96 exposes multiple serial ports over USB, but only one is typically configured for user interaction. The post explains how to use minicom to interact with the modem on its default port and outlines the process of switching to other ports, specifically the diagnostic port, using AT commands. This access allows for deeper interaction with the modem, enabling activities like firmware updates and more granular control, which are not possible through the default port. The author emphasizes the importance of switching back to the default port after completing tasks on the diagnostic port to restore normal functionality.
This blog post details the author's journey in establishing direct USB communication with the Qualcomm Quectel BG96 modem embedded within the RAKWireless RAK5010 WisBlock Core module. The primary motivation was to bypass the intermediate microcontroller of the RAK5010 and interact directly with the modem for improved control and potential performance benefits, specifically targeting direct access to the modem's GPS functionality.
The author initially encountered difficulties stemming from the RAK5010's default USB configuration. The onboard microcontroller, an STM32L476, typically manages USB communication, acting as a bridge to the BG96 modem. This setup prevents direct access to the modem's USB interface from an external computer.
The post meticulously outlines the steps taken to reconfigure the RAK5010 for direct modem access. This involved modifying the device's firmware to disable the STM32's USB functionality and reroute the USB data lines directly to the BG96 modem. The author provides specific instructions, including navigating the RAK5010's schematic to identify the relevant USB data lines (D+ and D-) and making the necessary hardware modifications. This involved desoldering specific resistors and bridging connections to physically reroute the USB signals.
Furthermore, the post explains the importance of identifying the correct USB port on the RAK5010 for this modification, highlighting that only one of the two available micro-USB ports provides access to the modifiable USB data lines.
Following the hardware modifications, the author describes the software configuration required to interact with the now-exposed BG96 modem. This includes utilizing the quectel-cm command-line tool, a utility specifically designed for communicating with Quectel modems. The post demonstrates the use of this tool to send AT commands directly to the BG96 modem, effectively showcasing the successful establishment of direct communication.
Finally, the post concludes by emphasizing the achieved objective of direct access to the BG96 modem, paving the way for finer-grained control and the possibility of bypassing limitations imposed by the intermediate microcontroller. The author hints at future exploration of the modem's capabilities, particularly its GPS functionality, now readily accessible through this direct USB connection.
Summary of Comments ( 0 )
https://news.ycombinator.com/item?id=43138637
Several commenters on Hacker News discussed practical aspects of using the RAK5010 and similar devices. Some questioned the practicality of USB tethering for IoT applications, citing power consumption concerns and suggesting alternative solutions like direct TCP/IP connections over cellular. Others shared personal experiences and insights, including one commenter who detailed their success using the RAK7200 with a Quectel modem and another who noted the complexities and lack of clear documentation around AT command interactions for specific modem features. A few comments also touched upon the security implications of exposing the modem via USB, particularly in commercial deployments. The overall sentiment reflected interest in the technical details but also a pragmatic awareness of the challenges involved in this approach.
The Hacker News post titled "Accessing the Qualcomm Modem over USB on the RAK5010" has generated a modest discussion with several interesting comments.
One commenter points out the potential security implications of exposing the modem's USB interface, highlighting the risk of unauthorized access and control if not properly secured. This concern is echoed by another user who questions the overall security posture of IoT devices, suggesting that many manufacturers prioritize features over robust security implementations.
Another commenter expresses appreciation for the detailed blog post, noting that it provides valuable insights into the inner workings of the RAK5010 and the Qualcomm modem. They also mention the challenges they faced while trying to achieve similar functionality, praising the author's clear explanations and step-by-step guide.
A further comment focuses on the broader context of cellular connectivity in IoT devices, discussing the advantages and disadvantages of using cellular networks compared to other technologies like LoRaWAN and Wi-Fi. They also touch upon the importance of selecting the right connectivity solution based on specific application requirements.
One user shares their experience with using the RAK5010 for a specific project, describing how they leveraged the modem's USB interface for data transmission. They also mention some of the limitations they encountered and suggest potential improvements for future iterations of the device.
Another commenter shifts the focus to the regulatory aspects of using cellular modems, highlighting the importance of complying with local regulations and obtaining the necessary certifications before deploying devices with cellular connectivity.
Finally, one commenter provides additional resources related to Qualcomm modems and USB communication, offering further reading for those interested in delving deeper into the technical details. They also suggest alternative approaches for accessing the modem's functionality, providing a broader perspective on the topic.
In summary, the comments section offers a mix of practical experiences, security considerations, regulatory insights, and technical discussions, providing valuable context and additional information related to the original blog post about accessing the Qualcomm modem on the RAK5010.