Freescale Semiconductor MK22FN256VDC12, Справочное руководство

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25.3.7 MCG Status Register (MCG_S)
Address: 4006_4000h base + 6h offset = 4006_4006h
Bit 7 6 5 4 3 2 1 0
Read LOLS0 LOCK0 PLLST IREFST CLKST OSCINIT0 IRCST
Write
Reset 0 0 0 1 0 0 0 0
MCG_S field descriptions
Field Description
7
LOLS0
Loss of Lock Status
This bit is a sticky bit indicating the lock status for the PLL. LOLS is set if after acquiring lock, the PLL
output frequency has fallen outside the lock exit frequency tolerance, D
unl
. LOLIE determines whether an
interrupt request is made when LOLS is set. LOLRE determines whether a reset request is made when
LOLS is set. This bit is cleared by reset or by writing a logic 1 to it when set. Writing a logic 0 to this bit has
no effect.
0 PLL has not lost lock since LOLS 0 was last cleared.
1 PLL has lost lock since LOLS 0 was last cleared.
6
LOCK0
Lock Status
This bit indicates whether the PLL has acquired lock. Lock detection is only enabled when the PLL is
enabled (either through clock mode selection or PLLCLKEN0=1 setting). While the PLL clock is locking to
the desired frequency, the MCG PLL clock (MCGPLLCLK) will be gated off until the LOCK bit gets
asserted. If the lock status bit is set, changing the value of the PRDIV0 [4:0] bits in the C5 register or the
VDIV0[4:0] bits in the C6 register causes the lock status bit to clear and stay cleared until the PLL has
reacquired lock. Loss of PLL reference clock will also cause the LOCK0 bit to clear until the PLL has
reacquired lock. Entry into LLS, VLPS, or regular Stop with PLLSTEN=0 also causes the lock status bit to
clear and stay cleared until the Stop mode is exited and the PLL has reacquired lock. Any time the PLL is
enabled and the LOCK0 bit is cleared, the MCGPLLCLK will be gated off until the LOCK0 bit is asserted
again.
0 PLL is currently unlocked.
1 PLL is currently locked.
5
PLLST
PLL Select Status
This bit indicates the clock source selected by PLLS . The PLLST bit does not update immediately after a
write to the PLLS bit due to internal synchronization between clock domains.
0 Source of PLLS clock is FLL clock.
1 Source of PLLS clock is PLL output clock.
4
IREFST
Internal Reference Status
This bit indicates the current source for the FLL reference clock. The IREFST bit does not update
immediately after a write to the IREFS bit due to internal synchronization between clock domains.
0 Source of FLL reference clock is the external reference clock.
1 Source of FLL reference clock is the internal reference clock.
Table continues on the next page...
Chapter 25 Multipurpose Clock Generator (MCG)
K22F Sub-Family Reference Manual , Rev. 3, 7/2014
Freescale Semiconductor, Inc. 543