HDMI Muxed Debug Port for Single USB Device
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Solution Overview
Problem
Conventional computing devices with limited USB ports face challenges in debugging due to the difficulty in expanding or upgrading, and existing solutions often require additional USB ports for debugging, which is not feasible in devices with a single USB port.
Innovation Solution
The implementation of a multiplexing system that uses an HDMI port to transmit and receive debug commands and data by detecting an extended display identification data (EDID) code, allowing debugging without increasing the number of USB ports through a muxed HDMI controller and UART, which disables the display data channel and utilizes serial lines for communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a computing device includes only a single USB port to maintain portability and small form factor, then portability is improved, but debugging capability deteriorates because there is insufficient port availability for both normal operations and debugging processes
Solution Approach 1:
The HDMI port is designed to serve dual purposes: normal display output functionality and debug port functionality. The HDMI controller detects when a debug cable is connected and automatically switches the port's function, allowing the same physical port to be used for both multimedia output and debugging operations, thereby eliminating the need for additional ports while maintaining debugging capability
Solution Approach 2:
A debug cable with a specific EDID code acts as an intermediary that triggers the functional switch of the HDMI port. When this special cable is detected, it mediates the transition of the HDMI port from display output mode to debug mode, enabling debugging access without requiring a separate dedicated debug port
2Adaptability or versatility
If multiple USB ports are included to provide sufficient debugging access, then debugging capability is improved, but device complexity and port count increase
Solution Approach 1:
The HDMI port is designed to serve dual purposes: normal display output functionality and debug port functionality. The HDMI controller detects when a debug cable is connected and automatically switches the port's function, allowing the same physical port to be used for both multimedia output and debugging operations, thereby eliminating the need for additional ports while maintaining debugging capability
Solution Approach 2:
The patent merges the display output function and debug port function into a single HDMI port interface. By combining these two previously separate functions into one unified port, the device reduces the total port count and simplifies the device structure while still providing both functionalities when needed
Data Source
AI summary
The muxed HDMI debug port methods and apparatuses are directed toward means for detecting an extended display identification data (EDID) code indicating a debug cable or debug host device coupled to the high-definition multimedia interface (HDMI) port of a computing device. In addition, the methods and apparatuses include means for disabling a display data channel (DDC) bus of the high-definition multimedia interface (HDMI) port in response to the extended display identification data (EDID) code indicating the debug cable or debug host device. Furthermore, the method and apparatuses include means for transmitting and receiving debug commands and data on a serial input (RXD) and serial output (TXD) of the high-definition multimedia interface (HDMI) port in response to the extended display identification data (EDID) code indicating the debug cable or debug host device.