Texas Instruments AM335 Series Technical Reference Manual

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18.3.7.1.2 Data Buffer Status
The data buffer status is defined in the following interrupt status register and status register:
• Interrupt status registers (see ):
– SD_STAT[29] BADA Bad access to data space
– SD_STAT[5] BRR Buffer read ready
– SD_STAT[4] BWR Buffer write ready
• Status registers (see ):
– SD_PSTATE[11] BRE Buffer read enable
– SD_PSTATE[10] BWE Buffer write enable
18.3.8 Transfer Process
The process of a transfer is dependent on the type of command. It can be with or without a response, with
or without data.
18.3.8.1 Different Types of Commands
Different types of commands are specific to MMC, SD, or SDIO cards. See the Multimedia Card System
Specification, the SD Memory Card Specifications, the SDIO Card Specification, Part E1, or the SD Card
Specification, Part A2, SD Host Controller Standard Specification for more details.
18.3.8.2 Different Types of Responses
Different types of responses are specific to MMC, SD, or SDIO cards. See the Multimedia Card System
Specification, the SD Memory Card Specifications, the SDIO Card Specification, Part E1, or the SD Card
Specification, Part A2, SD Host Controller Standard Specification for more details.
Table 18-13 shows how the MMC, SD, and SDIO responses are stored in the SD_RSPxx registers.
Table 18-13. MMC, SD, SDIO Responses in the SD_RSPxx Registers
Kind of Response Response Field Response Register
R1, R1b (normal response), R3, R4, R5, R5b, R6, R7 RESP[39:8]
(1)
SD_RSP10[31:0]
R1b (Auto CMD12 response) RESP[39:8]
(1)
SD_RSP76[31:0]
R2 RESP[127:0]
(1)
SD_RSP76[31:0]
SD_RSP54[31:0]
SD_RSP32[31:0]
SD_RSP10[31:0]
(1)
RESP refers to the command response format described in the specifications mentioned above.
When the host controller modifies part of the SD_RSPxx registers, it preserves the unmodified bits.
The host controller stores the Auto CMD12 response in the SD_RSP76[31:0] register because the Host
Controller may have a multiple block data DAT line transfer executing concurrently with a command. This
allows the host controller to avoid overwriting the Auto CMD12 response with the command response
stored in SD_RSP10 register and vice versa.
3369
SPRUH73H–October 2011–Revised April 2013 Multimedia Card (MMC)
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Texas Instruments AM335 Series Specifications

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Brand	Texas Instruments
Model	AM335 Series
Category	Computer Hardware
Language	English