Figure 314. Command Path State Machine (Sdio) - ST STM32F412 Reference Manual

Secure digital input/output interface (SDIO)
Pend
When the Wait state is entered, the command timer starts running. If the timeout is reached
before the CPSM moves to the Receive state, the timeout flag is set and the Idle state is
entered.
Note: The command timeout has a fixed value of 64 SDIO_CK clock periods.
If the interrupt bit is set in the command register, the timer is disabled and the CPSM waits
for an interrupt request from one of the cards. If a pending bit is set in the command register,
the CPSM enters the Pend state, and waits for a CmdPend signal from the data path
subunit. When CmdPend is detected, the CPSM moves to the Send state. This enables the
data counter to trigger the stop command transmission.
Note: The CPSM remains in the Idle state for at least eight SDIO_CK periods to meet the N
N timing constraints. N
RC
the minimum delay between the host command and the card response.
870/1163

Figure 314. Command path state machine (SDIO)

CPSM enabled and
pending command
CPSM disabled
Enabled and
command start
Last data
Send
Wait for response
is the minimum delay between two host commands, and N
CC
On reset
Idle
CPSM disabled
or no response
CPSM disabled or
command timeout
RM0402 Rev 6
Response received or
disabled or command
CRC failed
Response
started
Wait
RM0402
Receive
MS34444V1
and
CC
is
RC