Texas Instruments OMAP36 Series, Technical Reference Manual

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prcm-055
PRCM
sys_clkreq
sys_xtalin
sys_xtalout
sys_boot6
Oscillator
Internal clock request
PRM
OSC_SYS_CLK
Device
power FSM
Control
logic
Public Version
PRCM Functional Description
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Figure 3-59. System Clock Oscillator Controls
Table 3-37 lists the oscillator controls.
Table 3-37. Oscillator Controls
Oscillator Internal External Oscillator sys_clkreq sys_clkreq
(1)
Description
Mode Clock Clock State Pad Direction
Request
(1)
Request
(1)
Master Not asserted Not asserted Off Input and output Not asserted System clock not requested
internally (within the device)
or externally (by an external
device or peripheral)
Not asserted Asserted Active Input Asserted System clock is requested
externally only.
Asserted Not asserted Active Output Asserted System clock is requested
internally only.
Asserted Asserted Active Input and output Asserted System clock is requested
(driven internally by internally and externally.
device and externally
by peripheral)
Bypass Not asserted x
(2)
Bypass Input and output External clock System clock is not
(when external request state requested internally
request is not (sys_clkreq input has no
asserted) or input effect).
(when external
request is asserted)
Asserted x
(2)
Bypass Output (when only Asserted System clock is requested
internal request is internally (sys_clkreq input
asserted) or input and has no effect).
output (when external
and internal request
are asserted)
(1)
• If the PRCM. PRM_POLCTRL [1] CLKREQ_POL is set to active high (0x1), Asserted = 1, and Not asserted = 0.
• If the PRCM. PRM_POLCTRL [1] CLKREQ_POL is set to active low (0x0), Asserted = 0, and Not asserted = 1.
(2)
x indicates that the signal may be asserted or not asserted.
328 Power, Reset, and Clock Management SWPU177N – December 2009 – Revised November 2010
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