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AT32F413
Series Reference Manual
2022.06.27
Page 336
Rev 2.00
Figure 23-4
SDIO sequential read operation
Command
Response
From host
to card
From card
to host
Data stop operation
SDIO_D
SDIO_CMD
Response
Data stream
Data from
card to host
Stop command stops
data transfer
Data transfer operation
Command
Figure 23-5
SDIO sequential write operation
Command
Response
From
host
to card
From
card
to host
Data stop operation
SDIO_D
SDIO_CMD
Response
Data stream
Data from
host to
card
Stop command stops
data transfer
Data transfer operation
Command
23.3 SDIO main features
23.3.1 Card functional description
All the communications between the host and the cards are controlled by the card. The host sends two
different types of commands: broadcast command and addressible (point-to-point) command.
Broadcast command: applicable to all cards, some need responses
Addressible command: send to the addressible card, and response response from the card
Memory card defines two types of operational modes:
Card identification mode
Data transfer mode
23.3.1.1 Card identification mode
In card indentification mode, the host resets all cards, validates the operation voltage range, identifies
cards and sets a relative card address (RCA) for each card on the CMD. All communications in the card
identification mode use the command line (CMD).
Card identification process
The card identification process varies from card to card, and the host sends different commands. There
are SD, SDI/O and MMC cards. It is possible to send a CMD5 command to identify the type of a card. If
the host receives a response, it is a SDI/O card. If no response is received, the host will continue to send
ACMD41 command, if a response is received, it is a SD card, otherwise a MMC card.