Cmsemicon CMS32L051 - Precautions for Use

V1.2.2
CMS32L051 User Manual |Chapter 4 Clock Generation Circuit
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4.7.3.2 Operation setup flow
The operation start/stop flow when the high-speed internal oscillator clock frequency correction
function is used is shown in the following figure.
Figure 4-23 Operation mode setting process (example)
Note: The high-speed internal clock frequency correction Operation is performed repeatedly before
stopping the high-speed internal oscillator clock frequency correction function.
4.7.4 Precautions for use
4.7.4.1 SFR Access
Regarding the control of the FCST bit in the interval Operation mode, when writing 1 to the FCST bit,
you must first confirm that the value of the current FCST bit is 0 before writing 1 to it. Since hardware
clears priority, when writing 1 to the FCST bit immediately after the interval operation is completed (when
the interrupt generation is completed by high-speed internal resonance frequency correction), the
operation should be performed at least 1 cycle after the interrupt generation is completed after the high-
speed internal resonance frequency correction is completed.
4.7.4.2 Operation on reset
The high-speed internal oscillator clock frequency correction function must be stopped before entering
deep sleep.
Processing
execution
note
CRCTL=40H
Does the high speed internal
frequency correction
completion interrupt occur?
High speed internal frequency correction
continuous action mode setting
Allow high-speed internal frequency correction
completion interrupt
CRCTL=41H
Allow high-speed internal frequency
correction action
No
CRCTL=01H
High speed internal frequency correction
completion interrupt is prohibited
Yes
Action Start Process
CRCTL=00H
High speed internal vibration
frequency correction action stops
Action stop process
CRCTL=C0H
Does the high speed internal
frequency correction
completion interrupt occur?
High speed internal frequency correction interval
action mode setting
Allow high-speed internal frequency correction
completion interrupt
CRCTL=C1H
Allow high-speed internal frequency
correction action
No
High speed internal vibration
frequency correction completed
Yes
Does the high speed internal
frequency correction
completion interrupt occur?
CRCTL=C1H
Allow high-speed internal frequency
correction action
No
Yes
Action Start Process（2）
Timer interrupt, etc
＜Continuous action mode＞
Action Start Process（1）
＜Interval action mode＞
High speed internal vibration
frequency correction completed