Ver 1.3
PRELIMINARY
EAGLE
3.11
SD Card Controller
3.11.1 Features
- Supports SD Card (ver 1.1) / MMC (ver 3.31)
- Supports High Speed (50 MHz)
- Supports 1-bit / 4-bit data bus
- Supports DMA transfer
- Embedded 64-byte FIFO
- 40-bit Command Register
- 136-bit Response Register
3.11.2 Block Diagram
Figure 3-16 SDC Block Diagram
3.11.3 SD Bus Protocol
SD Bus protocol defines data transfer between SD Controller and SD Card through a 4-bit data line and 1-bit command
line. The basic unit of data transfer is called “Token”, which is composed of contents, start bit, end bit and CRC bits.
Token size varies according to the type of Token. There are three types of Token as described below:
Command : This token is used to start operation. Command is transferred from controller to SD Card through the CMD
line. There are two types of Commands, known as broadcast command and addressed command. Broadcast
command transfers data from controller to several SD card simultaneously while addressed command allows
data transfer from controller to a single SD Card pointed by an address.
Response : SD Card sends this token to controller as a respond to indicate the reception of command token. This is
transferred serially through CMD line.
Data : This token is transferred between controller and SD Card using Data line.
In SD bus protocol, the integrity of data transfer is guaranteed by CRC. CRC generation and error detection process are
implemented as hardware.
113
CONFIDENTIAL
Beijing Peak Microtech Co.Ltd.
ETC [ ETC ]
