SD卡物理层协议2.0中文翻译：SPI模式详解

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"SD Card物理层标准协议2.0第7章SPI模式的中文翻译" 本文档是SD卡物理层简化的规范版本2.0，由SD集团（包括松下、闪迪和东芝公司）和SD卡协会共同发布。这份文档主要涵盖了SD卡在SPI模式下的操作规范，SPI模式是一种广泛应用的串行通信接口，适用于简单系统或低数据速率应用。 SPI（Serial Peripheral Interface）模式是SD卡与主机系统之间通信的一种方式，相比于SD卡的默认的并行总线模式，SPI模式更为简洁，适合资源有限的设备使用。在SPI模式下，SD卡与主机之间的通信通常由四个信号线组成：串行时钟（SCLK）、主设备输入/从设备输出（MISO）、主设备输出/从设备输入（MOSI）和从设备选择（SS）。这些信号线负责数据传输、同步和设备选择。第7章详细讲述了SPI模式的具体操作流程和命令结构。在SPI模式下，SD卡的初始化过程包括了发送特定的命令序列，如CMD0（GO_IDLE_STATE）来将卡置于空闲状态，然后通过CMD8（SEND_IF_COND）进行版本检查。SPI模式下的数据传输通常是以块（block）为单位，每个块可以是512字节的数据。读写操作通过特定的命令（如CMD17用于读单块，CMD24用于写单块）发起，并且在传输过程中需要处理错误检测和纠正机制。 SPI模式还支持多卡操作，通过SS信号线可以单独选中一张卡进行通信。此外，SD卡在SPI模式下也支持高容量（HC）和扩展容量（XC）模式，这使得它们能够存储从几GB到几百GB的大量数据。此文档的2.0版本相较于1.10版本可能包含了一些更新和改进，比如对SPI模式的兼容性增强、错误处理机制的优化，或者是对新推出的产品特性的支持。然而，具体的变化没有在摘要中详细列出，需要查阅完整文档才能得知。这个SD卡物理层简化的2.0版本SPI模式规范对于理解如何在SPI接口上与SD卡进行有效通信至关重要，无论是硬件设计者还是嵌入式系统开发者，都需要熟悉这些规范以确保设备的兼容性和功能的正确实现。

Physical Layer Simplified Specification Version 2.00

3. SD Memory Card System Concept

Description here is a blank for the Simplified Specification.

3.1 Read-Write Property

In terms of read-write property, two types of SD Memory Cards are defined:

• Read/Write (RW) cards (Flash, One Time Programmable - OTP, Multiple Time Programmable -

MTP). These cards are typically sold as blank (empty) media and are used for mass data storage,

end user video, audio or digital image recording

• Read Only Memory (ROM) cards. These cards are manufactured with fixed data content. They are

typically used as a distribution media for software, audio, video etc.

3.2 Supply Voltage

In terms of operating supply voltage, two types of SD Memory Cards are defined:

• High Voltage SD Memory Cards that can operate within the voltage range of 2.7-3.6 V.

• Dual Voltage SD Memory Cards –Dual Voltage SD Memory Cards that can operate within the

voltage range of Low Voltage Range (T.B.D) and 2.7-3.6 V.

Note that details of Dual Voltage SD Memory Card will be defined in future specification.

3.3 Card Capacity

In terms of capacity, two types of SD Memory Cards are defined:

• Standard Capacity SD Memory Cards supports capacity up to and including 2 G bytes (2

bytes).

All versions of the Physical Specifications define the Standard Capacity SD Memory Card.

• High Capacity SD Memory Cards supports capacity more than 2 G bytes (2

bytes) and this version

of specification limits capacity up to and including 32 GB. High Capacity SD Memory Card is newly

defined from the Physical Layer Specification Version 2.00.

Only hosts that are compliant to the Physical Layer Specification version 2.00 or higher and the SD File

System Specification Ver2.00 can access High Capacity SD Memory Cards. Other hosts fail to initialize

High Capacity SD Memory Cards (See Figure 3-1).

Note:

1. The Part 1 Physical Layer Specification Version 2.00 and Part 2 File System Specification

Version 2.00 allow Standard Capacity SD Memory Cards to have capacity up to and

including 2 GB and High Capacity SD Memory Cards to have capacity up to and including

32 GB. SD Memory Cards with a capacity greater than 32 GB will be available with updated

versions of Part 1 and Part 2 Specifications.

2. Hosts that can access (read and/or write) SD Memory Cards with a capacity greater than 2

GB and up to and including 32 GB, shall also be able to access SD Memory Cards with a

capacity of 2 GB or less.

Physical Layer Simplified Specification Version 2.00

3.5 Bus Topology

This section is a blank for the Simplified Specification.

3.6 Bus Protocol

3.6.1 SD Bus

Communication over the SD bus is based on command and data bit streams that are initiated by a start

bit and terminated by a stop bit.

• Command: a command is a token that starts an operation. A command is sent from the host either

to a single card (addressed command) or to all connected cards (broadcast command). A command

is transferred serially on the CMD line.

• Response: a response is a token that is sent from an addressed card, or (synchronously) from all

connected cards, to the host as an answer to a previously received command. A response is

transferred serially on the CMD line.

• Data: data can be transferred from the card to the host or vice versa. Data is transferred via the

data lines.

Figure 3-2: “no response” and “no data” Operations

Card addressing is implemented using a session address, assigned to the card during the initialization

phase. The structure of commands, responses and data blocks is described in Chapter 4. The basic

transaction on the SD bus is the command/response transaction (refer to Figure 3-2). This type of bus

transaction transfers their information directly within the command or response structure. In addition,

some operations have a data token.

Data transfers to/from the SD Memory Card are done in blocks. Data blocks are always succeeded by

CRC bits. Single and multiple block operations are defined. Note that the Multiple Block operation mode

is better for faster write operation. A multiple block transmission is terminated when a stop command

follows on the CMD line. Data transfer can be configured by the host to use single or multiple data lines.

command response

block read operation

data stop operation

CMD

DAT

from

host

to card

stop command

stops data transfer

data from card

to host

from

card

to host

data block crc

data block crc data block crc

multiple block read operation

Figure 3-3: (Multiple) Block Read Operation

The block write operation uses a simple busy signaling of the write operation duration on the DAT0 data

line (see Figure 3-4) regardless of the number of data lines used for transferring the data.

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