![ARTERY AT32F435 Series Reference Manual Download Page 561](http://html1.mh-extra.com/html/artery/at32f435-series/at32f435-series_reference-manual_2977592561.webp)
AT32F435/437
Series Reference Manual
2022.11.11
Page 561
Rev 2.03
Figure 25-6
SDIO block diagram
AHB
Interface
AHB Bus
DMA_req
DMA_ack
SDIO_INT
SDIO Adapter
HCLK
SDIOCLK
Control unit
Command
Path
Data
Path
Adapter
Register
BUF
SDIO_CK
SDIO_CMD
SDIO_D [ 7:0 ]
25.3.3.1 SDIO adapter
SDIO_CK
is a clock to the MultiMedia/SD/SDIO car provided by the host. One bit of command or data
is transferred on both command and data lines with each clock cycle. The clock frequency can very
between different cards and different protocols.
MultiMedia card
―
V3.31 protocol 0
– 20MHz
―
V4.0/4.2 protocol 0
– 50MHz
SD card
―
0
– 50MHz
SD I/O card
―
0
– 50MHz
SDIO_CMD
is a bidirectional command channel and used for the initialization of a card and command
transfer. When the host sends a command to a card, the card will issue a response to the host. The
SDIO_CMD has two operational modes:
Open-drain mode for initialization (only for MMCV3.31 or previous)
Push-pull mode for command transfer (SD/SD I/O card and MMC V4.2 also use push-pull
drivers for initialization )
SDIO_D [7:0]
is a bidirectional data channel. After initialization, the host can change the width of the
data bus. After reset, the SDIO_D0 is used for data transfer by default. MMCV3.31 or previous supports
only one bit of data line, so only SDIO_DO can be used.
The table below is used for the MultiMedia card/SD/SD I/O card bus:
Table 25-18
SDIO pin definitions
Pin
Direction
Description
SDIO_CK
Output
MultiMedia card/SD/SDIO card clock. This pin is the clock from the
host to a card.
SDIO_CMD
Bidirectional
MultiMedia card/SD/SDIO card command. This pin is the
bidirectional command/response signal.
SDIO_D[7: 0]
Bidirectional
MultiMedia card/SD/SDIO card data. This pin is the
bidirectional databus.
Control unit
The control unit consists of a power management sub-unit and a clock management sub-unit. The power
management subunit is controlled by the SDIO_PWRCTRL register. The PS bit is used to define power-
up/power-off state. During the power-off and power-up phases, the power management subunit will
disable the card bus output signals. The clock management subunit is controlled by the SDIO_CLKCTRL