Figure 328. Control Unit - STMicroelectronics STM32F405 Reference Manual

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
The control unit is illustrated in
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.
1016/1731

Figure 328. Control unit

Control unit
Power management
Adapter
registers
To command and data path
Figure 328. It consists of a power management subunit and
DocID018909 Rev 11
Clock
SDIO_CK
management
RM0090
ai14804