K60P100M100SF2RM Datasheet, PDF (1654/1809 Pages) Freescale Semiconductor, Inc – K60 Sub-Family Reference Manual

Initialization/application of SDHC
52.6.3.3.1 Suspend
After setting the PROCTL[SABGREQ] bit, the host driver may send a suspend command
to switch to another function of the SDIO card. The SDHC does not monitor the content
of the response, so it doesn't know if the suspend command succeeded or not.
Accordingly, it doesn't de-assert read wait for read pause. To solve this problem, the
driver shall not mark the suspend command as a "suspend", (i.e. setting the
XFERTYP[CMDTYP] bits to 01). Instead, the driver shall send this command as if it
were a normal command, and only when the command succeeds, and the BS bit is set in
the response, can the driver send another command marked as "suspend" to inform the
SDHC that the current transfer is suspended. As shown in the following sequence for
suspend operation:
1. Set the PROCTL[SABGREQ] bit to pause the current data transfer at block gap.
2. After the IRQSTAT[BGE] bit is set, send the suspend command to suspend the
active function. The XFERTYP[CMDTYP] bit field must be 2'b00.
3. Check the BS bit of the CCCR in the response. If it is 1, repeat this step until the BS
bit is cleared or abandon the suspend operation according to the Driver strategy.
4. Send another normal I/O command to the suspended function. The
XFERTYP[CMDTYP] of this command must be 2'b01, so the SDHC can detect this
special setting and be informed that the paused operation has successfully suspended.
If the paused transfer is a read operation, the SDHC stops driving DAT2 and goes to
the idle state.
5. Save the context registers in the system memory for later use, including the DMA
system address register (for internal DMA operation), and the block attribute register.
6. Begin operation for another function on the SDIO card.
52.6.3.3.2 Resume
To resume the data transfer, a resume command shall be issued:
1. To resume the suspended function, restore the context register with the saved value
in step #5 of the suspend operation above.
2. Send the resume command. In the transfer type register, all bit fields are set to the
value as if this were another ordinary data transfer, instead of a transfer resume
(except the CMDTYP is set to 2'b10).
3. If the resume command has responded, the data transfer will be resumed.
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K60 Sub-Family Reference Manual, Rev. 6, Nov 2011
Freescale Semiconductor, Inc.