UM10503
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© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
438 of 1269
NXP Semiconductors
UM10503
Chapter 20: LPC43xx SD/MMC interface
The card detection signal is debounced based on the number of blocks specified in the
Debounce Count Register (DEBNCE). When this signal is connected to the card detect
pin of the card slot, then CDETECT register's bit 0 state will be filtered by the number of
debounce cycles specified in DEBNCE. This guarantees that interrupt related to the card
detect signal are debounced before occurring.
20.7.2 Auto-Stop
The auto-stop command helps to send an exact number of data bytes using a stream read
or write for the MMC, and a multiple-block read or write for SD memory transfer for SD
cards. The module internally generates a stop command and is loaded in the command
path when the SEND_AUTO_STOP bit is set in the Command register.
The software should set the SEND_AUTO_STOP bit according to details listed in table
below:
Table 330. SEND_AUTO_STOP bit
Card
Type
Transfer Type
Byte
Count
SEND_AUTO_
STOP bit set
Comments
MMC
Stream read
0
No
Open-ended stream
MMC
Stream read
>0
Yes
Auto-stop after all bytes transfer
MMC
Stream read
0
No
Open-ended stream
MMC
Stream read
>0
Yes
Auto-stop after all bytes transfer
MMC
Single-block read
>0
No
Byte count = 0 is illegal
MMC
Single-block write
>0
No
Byte count = 0 is illegal
MMC
Multiple-block read
0
No
Open-ended multiple block
MMC
Multiple-block read
>0
Yes
Pre-defined multiple block
MMC
Multiple-block write
0
No
Open-ended multiple block
MMC
Multiple-block write
>0
Yes
Pre-defined multiple block
SDMEM
Single-block read
>0
No
Byte count = 0 is illegal
SDMEM
Single-block write
>0
No
Byte count = 0 is illegal
SDMEM
Multiple-block read
0
No
Open-ended multiple block
SDMEM
Multiple-block read
>0
Yes
Auto-stop after all bytes transfer
SDMEM
Multiple-block write
0
No
Open-ended multiple block
SDMEM
Multiple-block write
>0
Yes
Auto-stop after all bytes transfer
SDIO
Single-block read
>0
No
Byte count = 0 is illegal
SDIO
Single-block write
>0
No
Byte count = 0 is illegal
SDIO
Multiple-block read
0
No
Open-ended multiple block
SDIO
Multiple-block read
>0
No
Pre-defined multiple block
SDIO
Multiple-block write
0
No
Open-ended multiple block
SDIO
Multiple-block write
>0
No
Pre-defined multiple block