Datasheet

Chapter 8 Multi-Purpose Clock Generator (S08MCGV1)
MC9S08DN60 Series Data Sheet, Rev 3
Freescale Semiconductor 137
8.3.4 MCG Status and Control Register (MCGSC)
7 654 3 210
R LOLS LOCK PLLST IREFST CLKST OSCINIT
FTRIM
W
POR:
Reset:
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
U
Figure 8-6. MCG Status and Control Register (MCGSC)
Table 8-4. MCG Status and Control Register Field Descriptions
Field Description
7
LOLS
Loss of Lock Status — This bit is a sticky indication of lock status for the FLL or PLL. LOLS is set when lock
detection is enabled and after acquiring lock, the FLL or PLL output frequency has fallen outside the lock exit
frequency tolerance, D
unl
. LOLIE determines whether an interrupt request is made when set. LOLS is cleared by
reset or by writing a logic 1 to LOLS when LOLS is set. Writing a logic 0 to LOLS has no effect.
0 FLL or PLL has not lost lock since LOLS was last cleared.
1 FLL or PLL has lost lock since LOLS was last cleared.
6
LOCK
Lock Status — Indicates whether the FLL or PLL has acquired lock. Lock detection is disabled when both the
FLL and PLL are disabled. If the lock status bit is set then changing the value of any of the following bits IREFS,
PLLS, RDIV[2:0], TRIM[7:0] (if in FEI or FBI modes), or VDIV[3:0] (if in PBE or PEE modes), will cause the lock
status bit to clear and stay cleared until the FLL or PLL has reacquired lock. Stop mode entry will also cause the
lock status bit to clear and stay cleared until the FLL or PLL has reacquired lock. Entry into BLPI or BLPE mode
will also cause the lock status bit to clear and stay cleared until the MCG has exited these modes and the FLL
or PLL has reacquired lock.
0 FLL or PLL is currently unlocked.
1 FLL or PLL is currently locked.
5
PLLST
PLL Select Status — The PLLST bit indicates the current source for the PLLS clock. 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 clock.
4
IREFST
Internal Reference Status — The IREFST bit indicates the current source for the 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 reference clock is external reference clock (oscillator or external clock source as determined by the
EREFS bit in the MCGC2 register).
1 Source of reference clock is internal reference clock.
3:2
CLKST
Clock Mode Status — The CLKST bits indicate the current clock mode. The CLKST bits do not update
immediately after a write to the CLKS bits due to internal synchronization between clock domains.
00 Encoding 0 — Output of FLL is selected.
01 Encoding 1 — Internal reference clock is selected.
10 Encoding 2 — External reference clock is selected.
11 Encoding 3 — Output of PLL is selected.