Start
Set the MMCi.MMCHS_SYSCTL[2]
CEN bit to 0x0 to not provide
the clock to the card
Write the
MMCi.MMCHS_SYSCTL[15:6]CLKD
with the new clock divider value
Set the MMCi.MMCHS_SYSCTL[2]
CEN bit to 0x1 to provide the clock to
the card
End
ICS = 0x1
Yes
Clock is stable
Read the MMCi.MMCHS_SYSCTL[1]
ICS bit
No
mmchs-042
Public Version
MMC/SD/SDIO Basic Programming Model
www.ti.com
Figure 24-45. MMC/SD/SDIO Controller Clock Frequency Change Flow
24.5.3 MMC/SD/SDIO1 Bus Voltage Selection
The MMC/SD/SDIO1 controller can operate with two types of card voltages: 1.8 V and 3.0 V. For this
reason, dual voltage pads are implemented on this interface. For technological concerns those pads must
have an internal bias voltage reference to operate. The PBIAS_LITE module supplies this bias voltage,
depending on the CONTROL.CONTROL_PBIAS_LITE register settings.
See
, Extended-Drain I/O Pin and PBIAS Cell, for more information about the PBIAS_LITE
cell.
, Extended-Drain I/Os and PBIAS Cell Basic Programming Guide, describes the steps
involved in transitioning from 1.8 V to 3.0 V and from 3.0 V to 1.8 V, applicable to the MMC/SD/SDIO1
controller.
CAUTION
The BIAS voltage must be set using the procedure described in
Extended-Drain I/Os and PBIAS Cell Basic Programming Guide. Failure to
follow this procedure can damage the MMCHS interface.
describes how to configure the MMCHS controller to fit with power switching sequence.
3410
MMC/SD/SDIO Card Interface
SWPU177N – December 2009 – Revised November 2010
Copyright © 2009–2010, Texas Instruments Incorporated