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MMC/SD/SDIO Register Manual
Bits
Field Name
Description
Type
Reset
21
HSS
High speed support. This bit indicates that the host controller supports
R
1
high speed operations and can supply an up-to-52 MHz clock to the card.
Read 0x0:
High Speed Not Supported
Read 0x1:
High Speed Supported
20:18
Reserved
Reserved bit field. Do not write any value.
R
0x0
17:16
MBL
Maximum block length. This value indicates the maximum block size that
R
0x1
the host driver can read and write to the buffer in the host controller.
The host controller supports 512 bytes and 1024 bytes block transfers.
Read 0x0:
512 bytes
Read 0x1:
1024 bytes
Read 0x2:
2048 bytes
15:14
Reserved
Reserved bit field. Do not write any value
R
0x0
13:8
BCF
Base clock frequency for clock provided to the card.
R
0x00
Read 0x0:
The value indicating the base (maximum) frequency for the
output clock provided to the card is system dependent and
is not available in this register. Get the information via
another method. See
, Power, Reset, and Clock
Management, for more information on the value of
FUNC_96M_CLK clock signal.
7
TCU
Timeout clock unit. This bit shows the unit of base clock frequency used to
R
1
detect Data Timeout Error (MMCi.
[20] DTO bit).
Read 0x0:
kHz
Read 0x1:
MHz
6
Reserved
Reserved. This bit is initialized to zero, and writes to it are ignored.
R
0
5:0
TCF
Timeout clock frequency. The timeout clock frequency is used to detect
R
0x00
Data Timeout Error (MMCi.
[20] DTO bit).
Read 0x0:
The timeout clock frequency depends on the frequency of
the clock provided to the card. The value of the timeout
clock frequency is not available in this register.
Note: You can have the timeout clock frequency by
dividing FUNC_96M_CLK by the value of the
MMCi.
[15:6] CLKD bit field.
Table 24-78. Register Call Summary for Register MMCHS_CAPA
MMC/SD/SDIO Integration
•
MMC/SD/SDIO Functional Description
•
:
MMC/SD/SDIO Basic Programming Model
•
Set MMCHS Default Capabilities
MMC/SD/SDIO Use Cases and Tips
•
:
MMC/SD/SDIO Register Manual
•
•
:
3459
SWPU177N – December 2009 – Revised November 2010
MMC/SD/SDIO Card Interface
Copyright © 2009–2010, Texas Instruments Incorporated