Adapter Device Preventing HDMI Alt-Mode Timeouts
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Solution Overview
Problem
The HDMI alt-mode experiences timeouts when no response is received within a predetermined period after an SCDC read request, leading to prohibited use of the SCDC read request function, which results in increased power consumption and bus bandwidth usage due to regular polling for status checks in HDMI source devices.
Innovation Solution
An adapter device that communicates with a sink device using HDMI and a source device using USB Type-C, by detecting the SCDC read request and driving the serial clock and data lines to a low level to prevent timeouts, allowing the adapter device to transmit the read request to the source device via USB Type-C, enabling the SCDC read request function without generating timeouts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polling is performed at regular intervals to conduct status check in HDMI source devices, then status check function is maintained, but power consumption increases and bus bandwidth increases
Solution Approach 1:
The adapter device implements a feedback mechanism where the sink device sends SCDC read requests to the adapter, which forwards them to the source device. The source device responds with status information, creating a feedback loop that eliminates the need for continuous polling while maintaining reliable status checking.
Solution Approach 2:
The adapter device serves as an intermediary between the sink device and source device. It receives SCDC read requests from the sink device, transmits them to the source device via USB Type-C, and forwards the status information back to the sink device, enabling efficient communication without requiring the source device to perform continuous polling.
2Reliability
If polling is performed at regular intervals to conduct status check in HDMI source devices, then status check function is maintained, but bus bandwidth increases
Solution Approach 1:
The feedback mechanism allows the sink device to request status information only when needed, rather than receiving continuous updates through polling. This on-demand approach reduces the amount of data transmitted over the bus while maintaining reliable status checking functionality.
Solution Approach 2:
The adapter device mediates the communication between sink and source devices, managing the bus bandwidth by forwarding SCDC read requests and status information only when necessary, rather than maintaining continuous polling traffic on the bus.
3Reliability
If SCDC read request function is used in HDMI alt-mode, then status check can be performed, but timeout occurs when no response is received within predetermined period
Solution Approach 1:
The adapter device acts as an intermediary that bridges the HDMI and USB Type-C communication protocols. It receives SCDC read requests from the sink device, translates and forwards them to the source device, and returns status information, thereby enabling reliable status checking without timeouts in HDMI alt-mode.
Solution Approach 2:
The adapter device ensures that SCDC read requests are properly formatted and transmitted to the source device in advance, with appropriate timing and protocol handling, preventing timeout conditions by ensuring timely response transmission.
Data Source
AI summary
An adapter device communicates with a sink device and a source device using first and second communication schemes, respectively. The adapter device includes: a transceiver receiving a state read request by detecting that a serial data line connected between the adapter device and the sink device is driven to a low level when a serial clock line connected therebetween is at a high level, and drive the serial data line to the low level and drive the serial clock line to a low level; a transmitter transmitting the state read request to the source device after the serial clock line is driven to the low level; and a receiver receiving a state read signal to read data of a state register in the sink device from the source device, wherein the transceiver transmits the state read signal to the sink device via the serial data line.