Information

Enhanced Secure Digital Host Controller
MPC8308 PowerQUICC II Pro Processor Reference Manual, Rev. 1
11-10 Freescale Semiconductor
8–9 CMDTYP Command type. There are three types of special commands: suspend, resume, and abort.
Clear this bit field for all other commands.
• Suspend command.
If the suspend command succeeds, the eSDHC assumes the SD bus has been released and
it is possible to issue the next command which uses the SD_DAT line. The eSDHC de-asserts
read wait for read transactions and stops checking busy for write transactions. In 4-bit mode,
the interrupt cycle starts.
If the suspend command fails, the eSDHC maintains its current state, and the host driver
should restart the transfer by setting PROCTL[CREQ]. The eSDHC does not check if the
suspend command succeeds or not. It is the host driver’s responsibility to issue a normal
CMD52 marked as suspend command when the suspend request is accepted by the card,
so that eSDHC can be informed that the SD bus is released and de-assert read wait during
read operation.
• Resume command. The host driver restarts the data transfer by restoring the registers saved
before sending the suspend command and sends the resume command. The eSDHC checks
for pending busy state before starting write transfers.
• Abort command.
If this command is set when executing a read transfer, the eSDHC stops reads to the buffer.
If this command is set when executing a write transfer, the eSDHC stops driving the SD_DAT
line.
After issuing the abort command, the host driver should issue a software reset. (Abort
transaction)
00 Normal—other commands
01 Suspend—CMD52 for writing bus suspend in the common card control register (CCCR),
defined in the SDIO Specification
10 Resume—CMD52 for writing function select in CCCR
11 Abort—CMD12, CMD52 for writing I/O abort in CCCR
10 DPSEL Data present select. Set to indicate that data is present and should be transferred using the
SD_DAT line. It is cleared for the following:
• Commands using only the SD_CMD line (e.g. CMD52)
• Commands with no data transfer but using busy signal on the SD_DAT[0] line (R1b or R5b,
e.g. CMD38)
Note: In resume command, this bit should be set while the other bits in this register should be
set the same as when the transfer initially launched.
0 No data present
1 Data present
11 CICEN Command index check enable.
0 Disable. The index field is not checked.
1 Enable. The eSDHC checks the index field in the response to see if it has the same value as
the command index. If it is not, it is reported as a command index error.
12 CCCEN Command CRC check enable. The number of bits checked by the CRC field value changes
according to the length of the response. (Refer to RSPTYP[1:0] and Table 11-8.)
0 Disable. The CRC field is not checked.
1 Enable. The eSDHC checks the CRC field in the response if it contains the CRC field. If an
error is detected, it is reported as a command CRC error.
13 — Reserved
Table 11-6. XFERTYP Field Descriptions (continued)
Bit Name Description