Emulated Serial Port via USB in BMC
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Solution Overview
Problem
Legacy serial ports are obsolete in modern CPU architectures, limiting IPMI functionality and serial communication capabilities, especially for devices like modems and dumb terminals, which still require serial interfaces.
Innovation Solution
An embedded-system device, such as a Baseboard Management Controller (BMC), emulates a serial port through a USB connection, allowing it to expose the serial port to a host computer, enabling communication by converting USB packets into serial data and vice versa using the USB Communications Device Class (CDC) protocol.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If legacy serial ports are removed from non-legacy systems, then system modernity and compliance with new CPU architectures is improved, but serial communication capability deteriorates
Solution Approach 1:
The patent implements a virtual serial port that copies the functionality of a legacy physical serial port through software emulation. The BMC presents a virtual COM port to the host system that mimics the behavior and interface of a traditional serial port, allowing serial communication protocols to function without requiring actual legacy hardware. This copying approach maintains compatibility with modern architectures while preserving serial communication capabilities.
Solution Approach 2:
The patent introduces a USB-to-serial intermediary device that acts as a bridge between the modern USB bus and serial communication protocols. This intermediary component translates USB packets into serial data format and vice versa, enabling serial communication functionality through a different physical interface. The intermediary layer allows the system to maintain serial port functionality without requiring legacy serial hardware.
2Reliability
If USB connection is used to emulate serial port, then serial communication functionality is restored, but device complexity increases
Solution Approach 1:
The BMC is designed with multi-functionality, serving both as a management controller and as a serial port emulator. By integrating the serial emulation capability into the existing BMC infrastructure, the patent avoids adding separate dedicated hardware and instead leverages the BMC's existing processing and communication capabilities to perform multiple functions including IPMI management and serial port emulation.
Solution Approach 2:
The virtual serial port implementation utilizes the BMC's existing USB interface and processing capabilities to provide serial emulation services without requiring external assistance or additional dedicated components. The BMC itself performs the emulation function using its built-in resources, making the system self-sufficient and reducing overall device complexity despite the added functionality.
Data Source
AI summary
In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be an embedded-system device. The apparatus may be an embedded-system device. The embedded-system device emulates a first serial port. The embedded-system device exposes the first serial port to a host of the embedded-system device through a USB connection. The embedded-system device receives first USB packets containing first command or data from the host through the USB connection. The embedded-system device inputs the first command or data to the first serial port.