eMMC的前世今生分析.ppt

Firmware:固件，一般存储在设备中的EEPROM（电可擦除只读存储器）或FLASH中，担任最基础、最底层任务的软件。固件通常无法被用户直接读取或修改，需要通过特定的刷新程序进行升级。 * Drive Strength:驱动强度,用来表示数据总线的信号强度，数值越高代表信号强度越高，增加信号强度可以提高超频的稳定性。 * eMMC 的结构及信号 eMMC 的结构及信号 CLK : Clock input . DAT0-7 : Bidirectional data channels , it operates in push-pull mode . RST_n : HW reset signal pin . VSS : Ground connections . VDDF(VCC) : Supply voltage for flash memory VDD(VCCQ) : Supply voltage for memory controller VDDi : Internal power node to stabilize regulator output to controller core logics (核心逻辑控制器). eMMC 的结构及信号 Data Strobe : Newly assigned pin for HS400 mode and generated from eMMC to host . In HS400 mode , read data and CRC response are synchronized with Data Strobe. CMD : A bidirectional signal used for device initialization and command transfers . command operates in two mode , open-drain for initialization and push-pull for fast command transfer . eMMC 内部分区 The device initially consists of two Boot Partitions and RPMB Partition and User Data Area. The User Data Area can be divided into four General Purpose Area Partitions and User Data Area partition. Each of the General Purpose Area partitions and a section of User Data Area partition can be configured as enhanced partition. eMMC 内部分区示意图 eMMC 内部分区 The size of Boot Area Partition 1 and 2 can not be set independently. It is set as same value . e·MMC adopts Enhanced User Data Area as SLC Mode. Therefore when master adopts some portion as enhanced user data area in User Data Area, that area occupies double size of original set up size. eMMC 未来趋势 eMMC下一个世代将会由UFS (Universal Flash Storage) 规格接棒。 UFS将提供极高的速度，接口速度可达300MB/s，以即时高速存储大型多媒体文件，传输一个90分钟的电影可以从3分钟降到几秒钟，同时在消费电子设备上使用时降低功耗。 感谢观赏eMMC基础篇 后续作品： 《eMMC 进阶篇》 《eMMC 高级篇》 《eMMC 超级篇》 《eMMC 无敌篇》 同类作品推荐 《我说你听，搞懂RAM不是事儿》 —— Candy_Liang 《手把手教你玩转CPU，从入门到精通》 —— Nature_Li 掌声 鲜花 EDC(Error Detection Code) 侦测机制 ECC (Error Correcting Code 除错机制 Wear Leveling