Wireless Image Transmission Device EDID Caching
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Solution Overview
Problem
The existing methods for switching wireless connections between video transmitting and receiving devices are slow due to the time-consuming process of reading and transmitting Extended Display Identification Data (EDID) using EEPROM, which is necessary for adapting video and audio signals to the capabilities of the receiving device.
Innovation Solution
An image transmission device that wirelessly transmits images with pre-stored format settings, allowing for immediate format conversion based on stored setting information without requesting EDID updates when the connection is established, and only updates EDID when notified of changes, thereby reducing the time required for connection switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the video receiving device reads and transmits EDID from EEPROM to adapt video signals to display capabilities, then the video format compatibility is ensured, but the connection switching time increases significantly
Solution Approach 1:
The video receiving device stores EDID data in a cache memory before it is actually needed during connection switching. By performing the EDID reading and storage operation in advance (when the device is first powered on or when EDID changes are detected), the system eliminates the need to read from slow EEPROM during critical connection switching moments, thus resolving the contradiction between ensuring format compatibility and reducing switching time
Solution Approach 2:
Instead of reading EDID directly from EEPROM during connection switching, the system creates a copy of the EDID data and stores it in a faster cache memory. This copying mechanism allows the video transmitting device to quickly access EDID information from the cache during switching operations, maintaining video format compatibility while significantly reducing the time penalty associated with EEPROM access
2Measurement precision
If the video transmitting device requests and processes EDID information during each connection establishment, then the display capabilities are accurately detected, but the overall system response speed decreases
Solution Approach 1:
The video receiving device performs the EDID preparation action in advance by storing the EDID data in cache memory before connection switching is needed. This preliminary action ensures that when connection establishment occurs, the EDID information is already available and ready for immediate use, thus improving connection speed without compromising the accuracy of display capability detection
Solution Approach 2:
The cache memory acts as an intermediary between the slow EEPROM and the fast processing requirements of connection switching. By introducing this intermediate storage layer, the system can maintain accurate display capability detection (by preserving the complete EDID data) while achieving faster connection establishment speeds (by accessing the cached copy rather than reading from EEPROM during switching)
Data Source
AI summary
When the wireless communication connection with the display device is established and the ROM stores the display device identifier for uniquely identifying the display device and the setting information so as to be associated with each other, a control unit causes the format of the image to change by the video signal processing unit based on the setting information stored in the ROM and causes the image whose format is changed to be wirelessly transmitted to the wireless communication circuit unit, without performing request for transmission of the setting information to the display device.