
NOTE
When a transition between run modes (RUN, HSRUN,
VLRUN) is required, the SCG should complete the switch to
the clock mode as defined in the SCG clock control register
first. Once the switch to the clock mode is completed, the
system can then initiate the request for the selected run mode.
For example, if a transition from RUN mode to VLRUN is
required, first complete any required clock change. Initiate the
VLRUN request after the clock change has completed.
The power modes are chip specific. For more details about power mode assignments, see
power management and system mode control information.
The modes of operation listed in the following table are the valid modes for this
implementation of the SCG.
Table 19-3. SCG modes of operation
Mode
Description
System Oscillator Clock
(SOSC)
System Oscillator Clock (SOSC) mode is entered when all the following conditions occur:
• RUN MODE: 0001 is written to RCCR[SCS].
VLRUN MODE: 0001 is written to VCCR[SCS].
HSRUN MODE: 0001 is written to HCCR[SCS].
• SOSCEN = 1
• SOSCVLD = 1
In SOSC mode, SCGCLKOUT and system clocks are derived from the external System Oscillator
Clock (SOSC).
Information regarding SOSC operation during normal and low power stop modes is found in the
.
Slow Internal Reference
Clock (SIRC)
Slow Internal Reference Clock (SIRC) mode is entered when all the following conditions occur:
• RUN MODE: 0010 is written to RCCR[SCS].
VLRUN MODE: 0010 is written to VCCR[SCS] and 1 is written to SIRCCSR[SIRCLPEN].
HSRUN MODE: 0010 is written to HCCR[SCS].
• SIRCEN = 1
• SIRCVLD = 1
In SIRC mode, SCGCLKOUT and system clocks are derived from the slow internal reference clock.
Two frequency ranges are available for SIRC clock as described in the SIRCCFG[RANGE] register
definition. Changes to SIRC range settings will be ignored when SIRC clock is enabled.
Information regarding SIRC operation during normal and low power stop modes is found in the
.
Fast Internal Reference
Clock (FIRC)
Fast Internal Reference Clock (FIRC) mode is the default clock mode of operation and is entered
when all the following conditions occur:
Table continues on the next page...
Functional description
Kinetis KE1xF Sub-Family Reference Manual, Rev. 4, 06/2019
482
NXP Semiconductors
Summary of Contents for KE1xF Series
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