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e.MMC
e•MMC v4.51
In June 2012 JEDEC published JESD84-B451: Embedded MultiMediaCard (e•MMC), Electrical Standard (Version 4.51). Continuing the evolution of e•MMC as an industry-leading memory standard for embedded non-volatile storage of system code, software applications and user data, the new v4.51 is a replacement of v4.5 which is now considered obsolete. JESD84-B451 is available for free download (with registration) at http://www.jedec.org/standards-documents/results/jesd84-b451.
JESD84-B451 e•MMC v4.51 contains errata corrections and clarifications of the v4.5 standard, adds details of the power supply requirements for e2MMC, defines pass through commands for extended security protocols, and brings back the definitions of Secure Trim and Secure Erase functionality that were previously removed from the e•MMC v4.5 standard for legacy backward compatibility, while maintaining the more favorable new alternate functions of Sanitize and Discard (introduced in v4.5) that allow improved performance and support of secure applications.
Other than the changes described above, e•MMC v4.51 maintains all functionality of the e•MMC v4.5 standard, which focuses on improving the interaction between the host processor and the memory device at the interface, configuration and protocol level, resulting in potential gains in overall system reliability.
The standard offers performance enhancement features, including an interface bandwidth increase from 104 Mbyte/sec to 200 MByte/sec. The command protocol is significantly improved with Packed Commands (the ability to group a series of commands in a single data transaction), Context ID (grouping different memory transactions under a single ID so the device can understand that they are related), and Data Tag (tagging specific write transactions so they can be prioritized and targeted to a memory region with higher performance and better reliability). The v4.51 standard also adds provision for volatile data cache, which can greatly reduce the latency between data transactions to improve performance.
Reliability enhancements include Power-Off Notification, which makes possible a more robust and safer power-down routine; as well as Dynamic Device Capacity, which provides a mechanism to increase device life time when the e•MMC device has reached its end-of-life, giving the user an opportunity to retrieve critical data from the device before disposal. The standard also adds the capability for the device to retrieve Real-Time Clock information from the host system, which may be used by the device internal memory management to improve data integrity and reliability.
In addition, e•MMC v4.51 provides features to better meet the requirements of the end applications, including enhanced partition attributes for system code and temporary data and separate data removal mechanisms. All performance and reliability enhancements offer designers additional options to improve system performance for the end user.
e•MMC v4.51 continues to support the current e•MMC ballout and adds a second e2MMC ballout that supports the Cache feature and 3 VDDi pins, which support an auxiliary storage medium (DRAM, Phase Change Memory, etc.) in the same device package. This enables manufacturers to fine-tune products by applying the best memory technology for a particular functionality and performance requirement.
e•MMC v4.41
In April 2010 JEDEC published JESD84-A441: Embedded MultiMediaCard (e•MMC) Product Standard v4.41. Version 4.41 contains corrections of critical errata found in the previous v4.4 specification, and offers optional features that designers may utilize to improve system performance. The v4.41 update is a replacement of v4.4 which is now considered obsolete.
In addition to features introduced with version 4.4 (doubling of memory interface performance, flexible partition management and increased security options), v4.41 offers options for enhancing device performance, including a high priority interrupt mechanism (HPI) and host-controlled background operations processing (BO).
About e•MMC
Designed for a wide range of applications in consumer electronics, mobile phones, handheld computers, navigational systems and other industrial uses, e•MMC is an embedded non-volatile memory system, comprised of both flash memory and a flash memory controller, which simplifies the application interface design and frees the host processor from low-level flash memory management. This benefits product developers by simplifying the non-volatile memory interface design and qualification process – resulting in a reduction in time-to-market as well as facilitating support for future flash device offerings. Small BGA package sizes and low power consumption make e•MMC a viable, low-cost memory solution for mobile and other space-constrained products.
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