STM32F101xx, STM32F102xx, STM32F103xx, STM32F105xx and ...

RM0008
Secure digital input/output interface (SDIO)
Control unit
The control unit contains the power management functions and the clock divider for the
memory card clock.
There are three power phases:
● power-off
● power-up
● power-on
Figure 184. Control unit
Control unit
Power management
Adapter
registers
Clock
management
SDIO_CK
To command and data path
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The control unit is illustrated in Figure 184. It consists of a power management subunit and
a clock management subunit.
The power management subunit disables the card bus output signals during the power-off
and power-up phases.
The clock management subunit generates and controls the SDIO_CK signal. The SDIO_CK
output can use either the clock divide or the clock bypass mode. The clock output is inactive:
●
●
●
after reset
during the power-off or power-up phases
if the power saving mode is enabled and the card bus is in the Idle state (eight clock
periods after both the command and data path subunits enter the Idle phase)
Command path
The command path unit sends commands to and receives responses from the cards.
Doc ID 13902 Rev 9 461/995