eMMC 4.4协议详解：高效开发eMMC存储的关键

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eMMC 4.4协议标准是由JEDEC（固态技术协会）制定的，它在2009年3月发布，旨在规范嵌入式多媒体卡（eMMC）的设计、功能和性能。这个标准对于eMMC存储设备的开发具有极高的实用价值，特别强调了高容量、可靠写入、启动、休眠模式以及双速数据传输能力的支持。eMMC 4.4标准还涵盖了多分区功能，并着重于增强安全特性。 MMCA（4.4）是这一标准的具体编号，即JESD84-A44，代表了JEDEC标准系列中的一个文档。JEDEC致力于通过消除制造商与消费者之间的误解，促进产品间的互换性和性能提升，帮助消费者在最短时间内选择到最适合自己的产品，无论在国内还是国际市场上使用，而不考虑可能涉及的专利问题。该标准的重要部分包括： 1. **接口规范**：eMMC 4.4定义了清晰的接口要求，确保不同品牌和厂商生产的eMMC产品能够互相兼容，便于集成到各种设备中。 2. **高容量支持**：随着技术的进步，标准允许更高的存储密度，满足现代设备对大容量存储的需求，如智能手机、平板电脑和游戏机等。 3. **可靠写入**：确保数据的稳定性和一致性，减少数据丢失的风险，这对于长时间运行和频繁使用的设备尤为重要。 4. **多种工作模式**：包括Boot模式用于启动设备，Sleep模式降低功耗，提高设备续航，而双速数据传输则提升了数据读写速度。 5. **分区管理**：支持多个独立的数据区域，方便系统管理，比如操作系统、用户数据和应用程序分开存放。 6. **安全增强**：考虑到存储数据的敏感性，eMMC 4.4包含加密技术和安全控制，保护用户隐私和数据安全。 7. **专利透明**：JEDEC在制定标准时不考虑专利影响，但不承担因采用标准可能导致的专利纠纷，这有利于市场的开放和创新。 eMMC 4.4协议标准为现代电子设备提供了一套全面且可靠的存储解决方案，不仅关注性能和容量，还注重用户体验和安全性。对于硬件开发者来说，理解和遵循这一标准至关重要，以确保他们的产品能满足市场的需求和期待。

JEDEC Standard No. 84-A44

-xii-

Embedded MultiMediaCard (e•MMC) e•MMC/Card Product Standard,

High Capacity, including Reliable Write, Boot, Sleep Modes, Dual Data

Rate, Multiple Partitions Supports and Security Enhancement

CONTENTS(continued)

Figure 39 — Block write command timing...............................................................................101

Figure 40 — Multiple-block write timing.................................................................................102

Figure 41 — Stop transmission during data transfer from the host...........................................102

Figure 42 — Stop transmission during CRC status transfer from the card...............................102

Figure 43 — Stop transmission after last data block; card is busy programming.....................103

Figure 44 — Stop transmission after last data block; card becomes busy ................................103

Figure 45 — Bus test procedure timing.....................................................................................104

Figure 46 — Boot operation, termination between consecutive data blocks ............................104

Figure 47 — Boot operation, termination during transfer.........................................................105

Figure 48 — Bus mode change timing (push-pull to open-drain).............................................105

Figure 49 — Alternative boot operation, termination between consecutive data blocks..........106

Figure 50 — Alternative boot operation, termination during transfer.......................................106

Figure 51 — H/W reset waveform ............................................................................................108

Figure 52 — Noise filtering timing for H/W reset ....................................................................108

Figure 53 — CRC7 generator/checker ......................................................................................154

Figure 54 — CRC16 generator/checker ....................................................................................155

Figure 55 — Bus circuitry diagram...........................................................................................159

Figure 56 — Improper power supply ........................................................................................160

Figure 57 — Shortcut protection...............................................................................................160

Figure 58 — Power-up diagram ................................................................................................161

Figure 59 — e•MMC power-up diagram ..................................................................................163

Figure 60 — The e•MMC power cycle .....................................................................................164

Figure 61 — MultiMediaCard bus driver..................................................................................166

Figure 62 — e•MMC internal power diagram...........................................................................168

Figure 63 — Bus signal levels...................................................................................................170

Figure 64 — Timing diagram: data input/output.......................................................................172

Figure 65 — Timing diagram: data input/output in dual data rate mode..................................175

Figure A.1 — Power supply decoupling .....................................................................................185

Figure A.2 — Modified MultiMediaCard connector for hot insertion........................................186

Figure A.3 — Legend for command-sequence flow charts.........................................................189

Figure A.4 — SEND_OP_COND command flow chart.............................................................190

Figure A.5 — CIM_SINGLE_CARD_ACQ...............................................................................191

Figure A.6 — CIM_SETUP_CARD...........................................................................................192

Figure A.7 — CIM_STREAM_READ .......................................................................................193

Figure A.8 — CIM_READ_BLOCK..........................................................................................193

Figure A.9 — CIM_READ_MBLOCK ......................................................................................194

Figure A.10 —CIM_WRITE_MBLOCK....................................................................................195

Figure A.11 —CIM_ERASE_GROUP .......................................................................................196

Figure A.12 —CIM_SECURE_ERASE......................................................................................197

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