Introduction of this chapter
A, SD bus, the transmission process
Second, the command and response format of the data inside the SD bus
Third, SDIO transmission, using a transmission data line 4 where
Four, CMD tables, and command the SD card required for communication Introduction
A, SD bus, the transmission process
The following look at SD bus (bus)
Reminder, SDIO communications, which will have lines CMD and DAT lines, respectively, to send commands and data transmission
The above operation is mimics some cases, is substantially the (CMD line) command is issued, SD card does not respond (CMD line), SD card or need to transmit data (DAT line), or not to send data to the host (DAT line)
Second, the command and response format of the data inside the SD bus
Third, SDIO transmission, using a transmission data line 4 where
If four data lines, transmission of FIG follows (if only one data line, a party can only slowly transmitted a)
Four, CMD tables, and command the SD card required for communication Introduction
Before explaining CMD table, first explain CMD divided into two types, application-specific command (ACMD) , General Command (GEN_CMD)
If you want to use the SD card manufacturer-specific commands, you need to before sending a specific command, sent first CMD55, taste a bit complex instruction
Here all the CMD, to pick some of the more commonly used, there is described together with Chinese, RESP response, points R1 ~ R7, pictures further below, SD card is not R4, R5 response , only a long response type R2
