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5.15
Low-Power Modes
SPRU751A
B15 acts as SYS_CLK_OUT. The procedure to enable SYS_CLK_OUT using
a hardware request is:
J
Set the TI_RESERVED_EN bit to 1 in the ULPD CLOCK_CTRL_REG
register.
J
Set
the
DIS_COM_MCLK_REQ
SOFT_DISABLE_REQ_REG register.
Consequently, the system clock is available on ball B15. Modifying the
SOFT_DIS_COM_MCLK_REQ or TI_RESERVED_EN bits masks out
MCLKREQ and deactivates MCLK clock.
SYS_CLK_OUT uses the same software request as the 48-MHz MCLK. The
procedure to enable SYS_CLK_OUT using a software request is:
J
Set ULPD CLOCK_CTRL_REG.TI_RESERVED_EN bit to 1
J
Set ULPD SOFT_DISABLE_REQ_REG.DIS_COM_MCLK_REQ to
1
J
Set ULPD SOFT_REQ_REG.SOFT_COM_REQ to 1
Consequently, the system clock appears on ball B15. By modifying
SOFT_COM_REQ or TI_RESERVED_EN bits, the software can deactivate
MCLK clock.
The ULPD module controls transitions to the two low-power modes referred
to as big sleep and deep sleep modes. Awake is the only active mode for which
OMAP3.2 can fetch instructions.
In addition, if some components are not used, they can be put in low-power
mode to reduce power dissipation.
OMAP5912 Clock Architecture
bit
to
0
in
the
Clocks
ULPD
59
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