eMMC EXT_CSD Register Clock Frequency Configuration
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Solution Overview
Problem
Conventional eMMC systems require a tuning process to adjust clock frequency, which increases host management overhead and is inefficient.
Innovation Solution
The eMMC system includes a command channel for receiving the SEND_EXT_CSD command, data channels for communicating maximum operating frequency information, and a clock channel that adjusts its frequency based on this information, allowing the host to generate a clock signal without performing a tuning process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tuning process is performed to adjust clock frequency, then the clock frequency can be appropriately matched to eMMC capabilities, but host management overhead increases
Solution Approach 1:
The maximum operating frequency information is pre-stored in the EXT_CSD register of the eMMC device. The host controller can query this information in advance using the SEND_EXT_CSD command, allowing the host to determine the appropriate clock frequency before actual data transfer operations begin, thereby avoiding the need for time-consuming tuning processes during operation.
Solution Approach 2:
The eMMC device provides feedback about its maximum operating frequency capabilities through the EXT_CSD register. The host controller uses this feedback information to automatically configure the appropriate clock frequency, eliminating the need for iterative tuning processes and reducing management overhead while ensuring reliable frequency matching.
2Speed
If a tuning process is performed to increase clock frequency, then data transfer rate can be improved, but the process takes additional time and reduces productivity
Solution Approach 1:
The maximum operating frequency information is prepared in advance and stored in the EXT_CSD register. The host controller queries this information using the SEND_EXT_CSD command during initialization, allowing the system to immediately configure the optimal clock frequency without performing time-consuming tuning processes, thus improving both data transfer rate and initialization efficiency.
Solution Approach 2:
The eMMC device itself provides the necessary frequency capability information through its EXT_CSD register, enabling the host controller to self-configure the appropriate clock frequency without requiring external tuning assistance or iterative adjustment processes, thereby improving productivity while achieving optimal data transfer rates.
Data Source
AI summary
An eMMC includes flash memory including an extended card specific data (CSD) register (“EXT_CSD register”), and an eMMC controller that controls operation of the flash memory. The eMMC controller is receives a clock from a host via a clock line, receives a SEND_EXT_CSD command from the host via a command line, and provides the host with eMMC information stored in the EXT_CSD register via a data bus in response to the SEND_EXT_CSD command, the eMMC information including maximum operating frequency information for the eMMC.