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SCM Programming Model
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•
Program a valid device OFF pads configuration, by setting in each CONTROL.
register all off mode values bits: OFFPULLTYPESELECT (OFF mode pull
type), OFFPULLUDENABLE (OFF mode pull enabling), OFFOUTVALUE (OFF mode output value),
OFFOUTENABLE (OFF mode output enabling), and OFFENABLE (OFF mode pad state override
control) .
•
Program a valid device ACTIVE pads configuration by setting pertinent bits in each CONTROL.
register (see
, Pad Configuration Programming Points).
•
Perform a device ACTIVE pads configuration saving in the save and restore memory from the wake-up
control module by asserting the STARTSAVE bit CONTROL.
•
Set the SCM in smart idle mode by setting the IDLEMODE bit field
CONTROL.
[4:3] (this ensures that its clocks cannot be cut until the save
procedure is complete).
•
Enable/disable the wake-up event detection capability of the pads by setting the WAKEUPENABLE bit
CONTROL.
NOTE:
When the wake-up detection is enabled for a pad, this pad is configured as input. Therefore,
do not forget to write 0b1 in the OFFOUTENABLE bit CONTROL.
to disable the output capability.
For further information, see
, Power, Reset, and Clock Management.
13.5.4 Pad Configuration Programming Points
To configure the pad, ensure that the following are done:
•
Identify signals required on the interface based on the target application.
Example: To configure the UART1 interface on balls, the required signals are uart1_tx, uart1_rts,
uart1_cts, and uart1_rx.
•
Choose the pads used for those signals. Some signals could be available on several pads and/or may
be multiplexed with other signals needed for another application. See
, Pad
Multiplexing Register Fields.
Example: Each UART1 interface signal is available on two pads. These signals are also multiplexed
with a McBSP signal.
Assume that the McBSP interface is required in the system. Therefore, for the UART1 interface
signals, pads must be used where those signals are not multiplexed with the McBSP signal.
•
Identify the pad configuration registers associated with the pads to be used in the application. See
, Pad Multiplexing Register Fields.
Example: Under the previous hypothesis, the pad configuration registers to program are:
–
uart1_cts: CONTROL.CONTROL_PADCONF_DSS_DATA0[15:0]
–
uart1_rts: CONTROL.CONTROL_PADCONF_DSS_DATA0[31:16]
–
uart1_tx: CONTROL.CONTROL_PADCONF_DSS_DATA6[15:0]
–
uart1_rx: CONTROL.CONTROL_PADCONF_DSS_DATA6[31:16]
NOTE:
In this configuration, dss_datan (where n = 0) signals are not available on these balls.
•
Configure
the
MUXMODE
field
of
each
pad
configuration
register
(CONTROL.
) associated with the pads used.
, Pad Multiplexing Register
Fields, lists the entire mode available for each pin. Write the binary value of the mode used in the
MUXMODE field of the pad configuration registers.
Example: UART1 signals are available in mode 2. Therefore, write 0b010 in the corresponding
MUXMODE field of the pad configurations registers to be programmed.
•
Configure the pull of the pad when used as input. When the pad is used as output, the pull is
automatically disabled.
, Pad Multiplexing Register Fields, lists the pull available on
each pad and it reset value. Set the appropriate value for the PULLTYPESELECT bit of the pad
configuration register to set the pull value (0b0 = Pull Down selected, 0b1 = Pull Up selected) and set
the PULLUDENABLE bit of the pad configuration register to enable the pull on the pad (0b0 = pull
2540
System Control Module
SWPU177N – December 2009 – Revised November 2010
Copyright © 2009–2010, Texas Instruments Incorporated