Sdio Bus Topology; Figure 176. Sdio "No Response" And "No Data" Operations; Figure 177. Sdio (Multiple) Block Read Operation - ST STM32F102 Series Reference Manual

RM0008
The current version of the SDIO supports only one SD/SDIO/MMC4.2 card at any one time
and a stack of MMC4.1 or previous.
19.2

SDIO bus topology

Communication over the bus is based on command and data transfers.
The basic transaction on the MultiMediaCard/SD/SD I/O bus is the command/response
transaction. These types of bus transaction transfer their information directly within the
command or response structure. In addition, some operations have a data token.
Data transfers to/from SD/SDIO memory cards are done in data blocks. Data transfers
to/from MMC are done data blocks or streams. Data transfers to/from the CE-ATA Devices
are done in data blocks.

Figure 176. SDIO "no response" and "no data" operations

Figure 177. SDIO (multiple) block read operation

SDIO_CMD
SDIO_D
From host to card(s)
SDIO_CMD Command
SDIO_D
Operation (no response)
From host to card From card to host
Command Response
Data block crc
Block read operation
Multiple block read operation
From host to card
Command
data from card to host
Data block crc
SDIO interface (SDIO)
From card to host
Response
Operation (no data)
ai14734
Stop command
stops data transfer
Command Response
Data block crc
Data stop operation
ai14735
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