sc9s12hy64j0vllr Freescale Semiconductor, Inc, sc9s12hy64j0vllr Datasheet - Page 271

• Manufacturer Part Number: sc9s12hy64j0vllr
• Description: S12 Microcontrollers Mcu 16-bit Hcs12 Cisc 32kb Flash 5v Tray
• Manufacturer: Freescale Semiconductor, Inc

7.4.5.2
A spike in the oscillator clock can disturb the function of the modules driven by this clock.
The adaptive Oscillator Filter includes two features:
Freescale Semiconductor
1. Filter noise (spikes) from the incoming external oscillator clock. The filter function is illustrated in
2. Detect severe noise disturbances on the external oscillator clock, which can not be filtered and
Figure
indicate the critical situation to the software by clearing the UPOSC and LOCK status bit and
setting the OSCIF and LOCKIF flag. An example for the detection of critical noise is illustrated in
Figure
OSCCLK
(filtered)
OSCCLK
(filtered)
OSCE
OSC
FILT
EXTAL
LOCK
UPOSC
OSCE
OSC
FILT
EXTAL
LOCK
UPOSC
The Adaptive Oscillator Filter
7-35.
7-36.
If the LOCK bit is clear due to severe noise disturbance on the external
oscillator clock the PLLCLK is derived from the VCO clock (with its actual
frequency) divided by four (see also
Divider Register
Figure 7-36. Critical noise detected by the Adaptive Oscillator Filter
0
0
Figure 7-35. Noise filtered by the Adaptive Oscillator Filter
enable external oscillator
configure the Oscillator Filter
enable external oscillator
configure the Oscillator Filter
> 0
> 0
MC9S12HY/HA-Family Reference Manual, Rev. 1.04
(CPMUPOSTDIV))
crystal/resonator starts oscillating
crystal/resonator starts oscillating
S12 Clock, Reset and Power Management Unit (S12CPMU) Block Description
NOTE
Section 7.3.2.3, “S12CPMU Post
phase shift can not be filtered but detected
filtered
filtered
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