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UM10503
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User manual
Rev. 1.3 — 6 July 2012
461 of 1269
NXP Semiconductors
UM10503
Chapter 20: LPC43xx SD/MMC interface
20.7.6.1.2
SD/MMC DMA descriptor DESC1
The DES1 descriptor contains the buffer size.
20.7.6.1.3
SD/MMC DMA descriptor DESC2
The DES2 descriptor contains the address pointer to the data buffer;
20.7.6.1.4
SD/MMC DMA descriptor DESC3
The DES3 descriptor contains the address pointer to the next descriptor if the present
descriptor is not the last descriptor in a chained descriptor structure or the second buffer
address for a dual-buffer structure.
29:6
-
Reserved
30
CES
Card Error Summary
These error bits indicate the status of the transaction to or from the card. These
bits are also present in RINTSTS Indicates the logical OR of the following bits:
•
EBE: End Bit Error
•
RTO: Response Time-out
•
RCRC: Response CRC
•
SBE: Start Bit Error
•
DRTO: Data Read Time-out
•
DCRC: Data CRC for Receive
•
RE: Response Error
31
OWN
When set, this bit indicates that the descriptor is owned by the SD/MMC DMA.
When this bit is reset, it indicates that the descriptor is owned by the Host. The
SD/MMC DMA clears this bit when it completes the data transfer.
Table 344. SD/MMC DMA DESC0 descriptor
Bit
Symbol
Description
Table 345. SD/MMC DMA DESC1 descriptor
Bit
Symbol
Description
12:0
BS1
Buffer 1 Size
Indicates the data buffer byte size, which must be a multiple of 4 bytes. In the
case where the buffer size is not a multiple of 4, the resulting behavior is
undefined. If this field is 0, the DMA ignores this buffer and proceeds to the next
descriptor in case of a chain structure, or to the next buffer in case of a
dual-buffer structure.
Remark:
If there is only one descriptor and only one buffer to be programmed,
use only the Buffer 1 and not Buffer 2.
25:13 BS2
Buffer 2 Size
These bits indicate the second data buffer byte size. The buffer size must be a
multiple of 4. Otherwise, the resulting behavior is undefined. This field is not
valid if DES0[4] is set.
31:26 -
Reserved
Table 346. SD/MMC DMA DESC2 descriptor
Bit
Symbol
Description
31:0
BAP1
Buffer Address Pointer 1
These bits indicate the physical address of the first data buffer. The SD/MMC
DMA ignores DES2 [1:0], corresponding to the bus width of 64/32/16, internally.