UM10503
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© NXP B.V. 2015. All rights reserved.
User manual
Rev. 2.1 — 10 December 2015
584 of 1441
NXP Semiconductors
UM10503
Chapter 22: LPC43xx/LPC43Sxx SD/MMC interface
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IDENTIFY DEVICE - Returns 512-byte data structure to the cpu that describes
device-specific information and capabilities. The cpu issues the IDENTIFY DEVICE
command only if the MMC block size is set to 512 bytes; any other MMC block size
has indeterminate results.
The cpu issues RW_REG for the ATA command, and the data is retrieved through
RW_BLK.
The cpu controller uses the following settings while sending RW_REG for the IDENTIFY
DEVICE ATA command. The following lists the primary bit
•
CMD register setting - data_expected field set to 0
•
CMDARG register settings:
–
Bit [31] set to 0
–
Bits [7:2] set to 128.
•
Task file settings:
–
Command field of the ATA task file set to ECh
–
Reserved fields of the task file cleared to 0
•
BLKSIZ register bits [15:0] and BYTCNT register - Set to 16
The cpu controller uses the following settings for data retrieval (RW_BLK):\
•
CMD register settings:
–
ccs_expect set to 1
–
data_expected set to 1
•
CMDARG register settings:
–
Bit [31] set to 0 (Read operation)
Data Count set to 1 (16'h0001)
•
BLKSIZ register bits [15:0] and BYTCNT register - Set to 512 IDENTIFY DEVICE can
be aborted as a result of the CPU issued CMD12.
–
READ DMA EXT - Reads a number of logical blocks of data from the device using
the Data-In data transfer protocol. The cpu uses RW_REG to issue the ATA
command and RW_BLK for the data transfer.
–
WRITE DMA EXT - Writes a number of logical blocks of data to the device using
the Data-Out data transfer protocol. The cpu uses RW_REG to issue the ATA
command and RW_BLK for the data transfer.
–
STANDBY IMMEDIATE - No data transfer (RW_BLK) is expected for this ATA
command, which causes the device to immediately enter the most aggressive
power management mode that still retains internal device context.
•
CMD Register setting - data_expected field set to 0
CMDARG register settings:
–
Bit [31] set to 1
–
Bits [7:2] set to 4
•
Task file settings: