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Registers
1298
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Multimedia Card (MMC)/Secure Digital (SD) Card Controller
26.4.2 MMC Memory Clock Control Register (MMCCLK)
The MMC memory clock control register (MMCCLK) is used to:
•
Select whether the MMCSD_CLK pin is enabled or disabled (CLKEN bit).
•
Select how much the function clock is divided-down to produce the memory clock (CLKRT bits). When
the MMCSD_CLK pin is enabled, the MMC controller drives the memory clock on this pin to control the
timing of communications with attached memory cards. For more details about clock generation, see
The MMC memory clock control register (MMCCLK) is shown in
and described in
.
Figure 26-18. MMC Memory Clock Control Register (MMCCLK)
31
16
Reserved
R-0
15
10
9
8
7
0
Reserved
DIV4
CLKEN
CLKRT
R-0
R/W-0
R/W-0
R/W
−
FFh
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 26-7. MMC Memory Clock Control Register (MMCCLK) Field Descriptions
Bit
Field
Value
Description
31-10
Reserved
0
Reserved
9
DIV4
DIV4 option
0
MMC clock = function clock/2 × (CLKRT + 1)
1
MMC clock = function clock/4 × (CLKRT + 1)
8
CLKEN
MMCSD_CLK pin enable
0
MMCSD_CLK pin is disabled and fixed low
1
The MMCSD_CLK pin is enabled; it shows the memory clock signal.
7-0
CLKRT
0
−
FFh
Clock rate. Use this field to set the divide-down value for the memory clock. The function clock is
divided down as follows to produce the memory clock:
memory clock frequency = function clock frequency/(2 × (CLKRT + 1) )