Chapter 7 eMMC Register

第七章 eMMC的寄存器

There are total seven Register in the eMMC device, which are OCR, CID, CSD, Ext_CSD, RCA, DSR and QSR. Most of them we have already cover in the separated topics. Here we only have a summary of them one by one.

在eMMC器件里一共有7个寄存器，他们是OCR, CID, CSD, Ext_CSD, RCA, DSR, QSR。我们在专门的话题中已经聊到过他们中的大多数。这里我们只是一个个来个总结。

Section 1 OCR CID RCA DSR QSR

第1节 OCR CID RCA DSR QSR

OCR is a 32-bit read only Operation Conditions Register, which contains the operating voltage and device access mode information. Besides these two, there is the most important bit-31 to indicate the power-up busy/ready status. OCR is in the R3 response for CMD1. But nowadays, operating voltage and device access mode are already fixed to support Dual voltage (1.8V and 3.3V) and Sector mode (512 Bytes). So the only thing left we need care is the power-up busy/ready status bit in R3 response when CMD1 polling.

OCR是一个32比特的只读运行条件寄存器，包含了运行电压以及器件访问模式信息。除了这两个，还有一个最重要的指示上电处于忙还是准备好的比特31。OCR 在CMD1的R3应答里。但是现在，支持双电压的运行电压和块模式（512字节）器件访问模式已经被固定了。所以唯一留下的我们需要关心就是CMD1轮询时在R3应答里的上电忙/准备好状态比特。

CID is a 128-bit read only Card IDentification Register, which contains the Device identification information. CID is in the R2 response for CMD2 and CMD10. CMD2 is a broadcast for all the eMMC devices in the eMMC bus, while CMD10 is a Unicast for the dedicated eMMC device with specific RCA (Relative Card Address) defined. Since for the eMMC nowadays, almost all the scenario we have only one eMMC device on the eMMC bus, so we can only focus on CMD2, no need for CMD10. We have below fields defined in CID.

CID是128比特只读的卡识别寄存器，包含了器件识别信息。CID在CMD2或者CMD10的R2应答里。CMD2是对于eMMC总线上所有的eMMC的广播，而CMD10是对于定义了RCA(相对卡地址)的特定的eMMC器件的单播。因为现在的eMMC器件，几乎所有的应用场景我们在eMMC总线上都只有唯一一个eMMC器件，所以我们只需要注意CMD2，没必要管CMD10。我们在CID里面有如下域。

MID (Manufacturer ID) field and OID (OEM ID) field are both 8-bit width, in which define the eMMC vendor information based on the JEDEC Standard Manufacturer’s Identification Code document (JEP106BB).

MID（生产厂商ID）域和OID（原始设备厂商 ID）域都是8比特宽度，里面定义了基于JEDEC标准厂商的识别号文档（JEP106BB）的eMMC的厂商信息。

CBX (Card, BGA or Others) field use 2 bits to define whether the package form factor is removable card, BGA chip or PoP (Package on Package).

CBX (卡，球形栅格整列或者其他) 域用两个比特定义了封装形式是可移除的卡片，还是BGA芯片，或者封装叠加（封装在封装之上）。

PNM (Product NaMe) is the 48-bit string of a 6 bytes ASCII characters code of the eMMC part number.

PNM（产品名字）是48比特的eMMC产品型号的ASCII码的字符串。

PRV (Product ReVision) is often used to record the eMMC device firmware version in the past. But since it is only 8-bit width, too limited nowadays to define the varies of firmware version, PRV is not used much and obsoleted now. The firmware version is now defined in the Ext_CSD vendor Specific field.

PRV (产品版本)过去通常被用作记录eMMC器件的固件版本。但是因为只有8比特位宽，对于现在众多的固件版本来说局限性太大，PRV现在用的不多以及过时了。固件版本现在通常在Ext_CSD的厂商专用域里面定义。

PSN (Product Serial Number) is a very import 32-bit unsigned integer number. PSN is a unique ID for this eMMC device. Together with the Manufacturer ID, each eMMC device could be tracked for the manufacturing information when there is some issue.

PSN (产品序列号)是一个十分重要的32比特无符号整形数据，PSN是一个eMMC的唯一识别号。和厂商ID一起配合，每一个eMMC器件都可以在出问题的时候追溯回制造信息。

MDT (Manufacturing DaTe) is an 8-bit wide data which contains the manufacturing year and month information of this eMMC device.

MDT (制造日期)是一个8比特位宽的数据，包含了eMMC器件制造的年月信息。

The last 8-bit is 7-bit CRC and 1-bit stuff ‘1’. Since the CID already contains the 7-bit CRC internally, this is the reason that R2 response do not need extra CRC7 anymore.

最后8bite是7bit的CRC以及1bite的填充‘1’。因为CID里面已经包含了7比特的CRC，这是为什么R2应答不再需要额外的CRC-7.

RCA (Relative Card Address) is a writable 16-bit register used as CMD7 argument to define the eMMC device address, default is 0x0001. When CMD7 with argument RCA 0x0000 issued, the eMMC device will enter Stand-by State as deselected. Usually other RCA value is not used since there is often only one eMMC device in the eMMC bus.

RCA（相对卡地址）是一个可改写的16位寄存器，作为CMD7参数来定义eMMC器件的地址，默认值是0x0001。当CMD7带参数RCA 0x0000发出，eMMC器件将会被取消选定进入等待状态。通常其他的RCA值不会被使用因为eMMC总线上经常只用一个eMMC器件。

DSR (Driver Stage Register) is also a writable 16-bit register used as CMD4 argument, but it is optional, not mandatory to implement. It is mainly for the signal Integrity improvement purpose to change the eMMC device output data lines rising and falling time. It is not common to change DSR, but when Tuning failed, DSR will be changed sometimes to get a more stable and reliable host receiver sampling point.

DSR（驱动等级寄存器）同样是一个16比特的可写的寄存器作为CMD4的参数，但是这个是可选的，不是强制要求实现的。这个的目的主要是改变eMMC器件发送数据信号线的上升和下降时间而提升信号完整性。通常不会改变DSR，但是一旦tuning失败，DSR有时会被改变来获取更加稳定和可靠的主机接收器采样点。

QSR (Queue Status Register) is the 32-bit read only register in the CMD13 R1 response when CMD13 argument bit 15 set to ‘1’. QSR could indicate which queue out of total 32 is ready for receiving command.

QSR（队列状态寄存器）是一个当CMD13参数比特15设置为‘1’时，在CMD13 R1应答里的32比特只读寄存器。QSR可以标识32个队列里面的哪一个准备好接受命令。

The five Registers mentioned above are quite simple, the only thing need to be noted is how to distinguish which one of these 5 register is read-only and which one is writable. The simple rule is to see where the register is, if it is in the command argument, then it is writable. If it is in the response, it is read-only.

以上提到的5个寄存器比较简单，唯一要注意的是如何区分这5个寄存器里哪一个是只读的，哪一个是可写的。一个简单的规则是看寄存器在哪里，如果是在命令的参数里面，那么就是可写的。如果是在应答里面，那么就是只读的。

In the next sub-topic of Register, we will turn to CSD (Card Specific Data) and Ext_CSD (Extended CSD). These buddies are much more complex than the five register above, which contain much more field either readable or writable. Especially the Ext_CSD, it is a core register representing of the eMMC device’s various of features.

在下一个寄存器的子话题，我们将转向CSD（卡专用数据）和Ext_CSD（扩展的CSD）。这哥俩比以上的5个寄存复杂的多，包含多的多的可读或者可写地域。特别是Ext_CSD，这个是反映eMMC器件多种多样特性的核心寄存器。