Information

Boot operation will be terminated when all contents of the enabled boot data are sent to
the master. After boot operation is executed, the slave shall be ready for CMD1 operation
and the master needs to start a normal MMC initialization sequence by sending CMD1.
DAT[0]
CMD
CLK
50ms
max
1 sec.max
010
S
SS
E
EE
CMD1
RESP
CMD2
RESP
CMD3
RESP
512bytes
+CRC
512bytes
+CRC
Boot termininted
Min 8 clocks + 48 clocks = 56 clocks required from
CMD singal high to next MMC command
Figure 49-37. Multimediacard state diagram (normal boot mode)
49.5.9.2 Alternative boot operation
This boot function is optional for the device. If bit 0 in the extended CSD byte[228] is set
to '1', the device supports the alternative boot operation.
After power-up, if the host issues CMD0 with the argument of 0xFFFFFFFA after 74
clock cycles, before CMD1is issued or the CMD line goes low, the slave recognizes that
boot mode is being initiated and starts preparing boot data internally.
Within 1 second after CMD0 with the argument of 0xFFFFFFFA is issued, the slave
starts to send the first boot data to the master on the DAT line(s).
If boot acknowledge is enabled, the slave has to send the acknowledge pattern '010' to the
master within 50ms after the CMD0 with the argument of 0xFFFFFFFA is received. If
boot acknowledge is disabled, theslave will not send out acknowledge pattern '010'.
The master can terminate boot mode by issuing CMD0 (Reset).
Boot operation will be terminated when all contents of the enabled boot data are sent to
the master. After boot operation is executed, the slave shall be ready for CMD1 operation
and the master needs to start a normal MMC initialization sequence by sending CMD1.
Functional description
K20 Sub-Family Reference Manual, Rev. 6, Nov 2011
1450 Freescale Semiconductor, Inc.