UM10503
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© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
444 of 1269
NXP Semiconductors
UM10503
Chapter 20: LPC43xx SD/MMC interface
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Check if response_timeout error, response_CRC error, or response error is set.
This can be done either by responding to an interrupt raised by these errors or by
polling bits 1, 6, and 8 from the RINTSTS register @0x44. If no response error is
received, then the response is valid. If required, the software can copy the
response from the response registers @0x30-0x3C.
Software should not modify clock parameters while a command is being executed.
20.7.4.5 Data Transfer Commands
Data transfer commands transfer data between the memory card and the Module. To send
a data command, the Module needs a command argument, total data size, and block size.
Software can receive or send data through the FIFO.
Before a data transfer command, software should confirm that the card is not busy and is
in a transfer state, which can be done using the CMD13 and CMD7 commands,
respectively.
Table 331. CMD register settings for No-Data Command
Name
Value
Comment
start_cmd 1
update_clock_ registers_only
0
No clock parameters update command
card_number
0
Card number in use. Only zero is possible
because one card is support.
Data_expected
0
No data command.
Send_initialization
0
Can be 1, but only for card reset commands,
such as CMD0
stop_abort_cmd
0
Can be 1 for commands to stop data transfer,
such as CMD12
Cmd_index
Command index
Response_length
0
Can be 1 for R2 (long) response
Response_expect
1
Can be 0 for commands with no response; for
example, CMD0, CMD4,
CMD15, and so on
User-selectable
Wait_prvdata_complete
1
Before sending command on command line,
cpu should wait for
completion of any data command in process,
if any (recommended to
always set this bit, unless the current
command is to query status or stop
data transfer when transfer is in progress)
Check_response_crc
1
0 – Do not check response CRC
1 – Check response CRC
Some of command responses do not return
valid CRC bits. Software should disable CRC
checks for those commands in order to
disable CRC checking by controller.