S12 Clock, Reset and Power Management Unit (S12CPMU_UHV_V8)
MC9S12VRP Family Reference Manual Rev. 1.3
124
NXP Semiconductors
4.3.2.6
S12CPMU_UHV_V8 Clock Select Register (CPMUCLKS)
This register controls S12CPMU_UHV_V8 clock selection.
Read: Anytime
Write:
5. Only possible if PROT=0 (CPMUPROT register) in all MCU Modes (Normal and Special Mode).
6. All bits in Special Mode (if PROT=0).
7. PLLSEL, PSTP, PRE, PCE, RTIOSCSEL: In Normal Mode (if PROT=0).
8. CSAD: In Normal Mode (if PROT=0) until CPMUCOP write once has taken place.
9. COPOSCSEL0: In Normal Mode (if PROT=0) until CPMUCOP write once has taken place.
If COPOSCSEL0 was cleared by UPOSC=0 (entering Full Stop Mode with COPOSCSEL0=1 or
insufficient OSCCLK quality), then COPOSCSEL0 can be set once again.
10. COPOSCSEL1: In Normal Mode (if PROT=0) until CPMUCOP write once has taken place.
COPOSCSEL1 will not be cleared by UPOSC=0 (entering Full Stop Mode with
COPOSCSEL1=1 or insufficient OSCCLK quality if OSCCLK is used as clock source for
other clock domains: for instance core clock etc.).
NOTE
After writing CPMUCLKS register, it is strongly recommended to read
back CPMUCLKS register to make sure that write of PLLSEL,
RTIOSCSEL and COPOSCSEL was successful.
NOTE
When using the external oscillator (OSCE=1) as system clock (write
PLLSEL = 0) it is highly recommended to enable the oscillator clock
monitor reset feature (write OMRE = 1 in CPMUOSC2 register). If the
oscillator monitor reset feature is disabled (OMRE = 0) and the external
oscillator clock is used as system clock, the system might stall in case of loss
of oscillation.
0x0039
7
6
5
4
3
2
1
0
R
PLLSEL
PSTP
CSAD
COP
OSCSEL1
PRE
PCE
RTI
OSCSEL
COP
OSCSEL0
W
Reset
1
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 4-9. S12CPMU_UHV_V8 Clock Select Register (CPMUCLKS)
Summary of Contents for MC9S12VRP64
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