Altera cyclone V Technical Reference page 1007

cv_5v4
2016.10.28
1. Check that the card is not in a transfer state, which confirms that the bus is free for data transfer.
2. If the card is in a disconnect state, select it using the SD/SDIO SELECT/DESELECT_CARD command.
The card status can be retrieved in response to an IO_RW_DIRECT or IO_RW_EXTENDED
command.
3. Check that a function to be resumed is ready for data transfer. Determine this state by reading the
corresponding RF<n> flag in CCCR at offset 0x0F of the card. If RF<n> = 1, the function is ready for
data transfer.
Note: For detailed information about the RF<n> flags, refer to SDIO Simplified Specification Version
2.00, available on the SD Association website.
4. To resume transfer, use the IO_RW_DIRECT command to write the function number at the FSx bits in
the CCCR, bits 3:0 at offset 0x0D of the card. Form the command argument for the IO_RW_DIRECT
command and write it to the
Table 14-27: cmdarg Bit Values for RESUME Command
Bits
31
30:28
27
26
25:9
8
7:0
5. Write the block size value to the
6. Write the byte count value to the
bytes to be transferred. It is the responsibility of the software to handle the data.
To determine the number of pending bytes to transfer, read the transferred CIU card byte count
register (
bytes to transfer.
7. Write to the
command is sent and the function resumes data transfer. For more information, refer to Single-Block or
Multiple-Block Read and Single-Block or Multiple-Block Write.
8. Read the resume data flag (DF) of the SDIO card device. Interpret the DF flag as follows:
• DF=1—The function has data for the transfer and begins a data transfer as soon as the function or
memory is resumed.
• DF=0—The function has no data for the transfer. If the data transfer is a read, the controller waits
for data. After the data timeout period, it issues a data timeout error.
Related Information
SD Association
•
To learn more about how SD technology works, visit the SD Association website (www.sdcard.org).
SD/MMC Controller
Send Feedback
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cmdarg
R/​W flag
Function number
RAW flag
Don't care
Register address
Don't care
Write data
blksiz
bytcnt
). Subtract this value from the total transfer size to calculate the number of remaining
tcbcnt
†
register similar to a block transfer operation. When the
cmd
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register. Bit values are listed in the following table.
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Content
register. Data is transferred in units of this block size.
register. Specify the total size of the data that is the remaining
†
Resume
†
Value
1
0, for CCCR access
1, read after write
-
0x0D
-
Function number that is to be
resumed
†
register is written, the
cmd
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Altera Corporation
14-61
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