SD Card Combined Addressing Beyond the 32-Bit Capacity Limit
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Solution Overview
Problem
The existing Secure Digital (SD) cards are limited to a maximum storage capacity of 2 terabytes due to the 32-bit address parameter in their command, which restricts their addressing and accessing capabilities.
Innovation Solution
An addressing method is introduced that extends the 32-bit address by combining it with an additional address to form a combined address of more than 32 bits, allowing access to memory capacities greater than 2 TB, using address extension commands like CMD22 to combine with access commands such as CMD17, CMD18, CMD24, CMD25, CMD32, CMD33, or CMD44, enabling operations like single read, single write, multiple read, multiple write, and erase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a 32-bit address parameter is used in SD card commands, then the device complexity is reduced and compatibility is maintained, but the storage capacity is limited to 2 TB
Solution Approach 1:
The patent segments the address into two parts: a first address (upper address) and a second address (lower address). The first address is transmitted via an address extension command (e.g., CMD22), and the second address is transmitted via the access command (e.g., CMD17, CMD24). This segmentation allows the system to exceed the 32-bit address limitation while maintaining compatibility with existing 32-bit address infrastructure.
Solution Approach 2:
The patent performs preliminary action by sending the address extension command (first address) before the access command (second address). This preliminary transmission of the upper address portion allows the system to prepare the extended address space before executing the actual memory access operation, enabling capacities beyond 2 TB.
2Quantity of substance
If the address parameter is extended beyond 32 bits, then the storage capacity support is increased to 128 TB or 232 TB, but the command structure and addressing method become more complex
Solution Approach 1:
The patent makes the command structure universal by designing it to work with both traditional 32-bit addresses and extended addresses beyond 32 bits. The address extension command framework can accommodate variable-length first addresses (e.g., 6 bits to 32 bits) combined with standard 32-bit second addresses, allowing the same command structure to serve multiple capacity ranges.
3Quantity of substance
If an address extension command is introduced, then the storage capacity is extended beyond 2 TB, but the number of commands and communication steps increases
Solution Approach 1:
The address extension command performs preliminary action by pre-transmitting the upper address portion before the actual data access command. This allows the host controller to prepare the extended address information in advance, so that when the access command is executed, the full 64-bit address is already assembled and ready for immediate memory access, minimizing additional access time.
Data Source
AI summary
The present invention provides a method for accessing a secure digital (SD) card, which includes a voltage supply pin for receiving voltage supply from a host, at least one ground pin, a command pin for receiving a command from a host, and four data pins for writing data into the SD card or reading data from the SD card. The method includes receiving, via the command pin, an address extension command including a first address from a host, receiving, via the command pin, an access command including a second address from a host, and accessing, via the data pins, at least a memory location of the SD card indicated by a third address, which is a combination of the first address and the second address. The access command indicates an access operation to be performed on the SD card.