Information

Wait SDHC interrupt
Yes, card presents
No card presents
(2)
Enable card detection irq
Voltage validation
C
heck
CINS
I
RQ
STAT
[ ]
Clear CINSIEN
to
dis
able card detection irq
(
1
)
Figure 49-39. Flow diagram for card detection
Here is the card detection sequence:
• Set the CINSIEN bit to enable card detection interrupt
• When an interrupt from the SDHC is received, check the IRQSTAT[CINS] bit in the
Interrupt Status register to see if it was caused by card insertion
• Clear the CINSIEN bit to disable the card detection interrupt and ignore all card
insertion interrupts afterwards
To detect a CE-ATA device, after completing the normal MMC reset and initialization
procedures, the host driver shall issue CMD 60 to check for a CE-ATA signature. If the
device responds to the command with the CE-ATA signature, a CE-ATA device has been
found. Then the driver should query EXT_CSD register byte 504 (S_CMD_SET) in the
MMC register space. If the ATA bit (bit 4) is set, then the MMC device is an ATA
device. If the device indicates that it is an ATA device, the Driver should set the ATA bit
(bit 4) of the EXT_CSD register byte 191 (CMD_SET) to activate the ATA command set
for use. To choose the command set, the driver shall issue CMD6. It is possible that the
CE-ATA device does not support the ATA mode, so the driver shall not issue ATA
command to the device.
49.6.2.2 Reset
The host consists of three types of resets:
• Hardware reset (card and host) which is driven by POR (power on reset)
Chapter 49 Secured digital host controller (SDHC)
K20 Sub-Family Reference Manual, Rev. 6, Nov 2011
Freescale Semiconductor, Inc. 1453