BAT32G1x9 user manual | Chapter 4 Clock generation circuit
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Rev.1.02
4.7.3
Description of the operation
4.7.3.1
Operation summary
The high-speed internal oscillation frequency correction function uses the sub-system clock (fSUB) as the
reference to generate a correction period, measures the frequency of the high-speed internal oscillation, and
corrects the frequency accuracy of the high-speed internal oscillation in real time. Clock adjusts the operation of
the repeating frequency measurement phase and the frequency correction phase. The correction calculus is
performed during the frequency measurement phase, and the correction values reflecting the results of the
correction calculus are saved during the frequency correction phase.
Table 4-11is the high-speed internal vibration input frequency and correction period, and Figure Fig. 4-25is the
timing diagram of the high-speed internal vibration frequency correction operation (detailed).
Table 4-11High-speed internal oscillator input frequency and correction period
fHOCO (MHz)
FRQSEL4-FRQSEL3
Note
Correction Period (ms)
64
11
31.2
(Frequency measurement phase +
frequency correction phase)
48
10
32
01
24
00
Note: FRQSEL4-FRQSEL3 is bit4-bit3 for option bytes0 0C2H
During the frequency measurement phase of the correction period, the frequency of the high-speed internal
oscillation is corrected according to the size of the count value and the expected value.
Fig. 4-25
High-speed internal oscillation frequency correction action timing diagram (detailed).
Note: The basic operation of the continuous action mode and the interval action mode are the same.
The difference is whether the FCST bit is cleared by software or hardware. In addition, only the
system reset can clearly correct the correction value.
f
HOCO
=32MHz
f
IH
(32MHz)
Reference
clock
(fsub/2^9)
CRST
(Action enabling
position)
20 bit count
register
31.25nS
15.6mS
Count enable
Correction
value
[6:0]
"0000000B"
"0000001B"(former value
"0000000B"+1)
Count Start
15.6mS
Measurement
phase
Count End
(Keep the count
value)
Count Start
Correction
phase
31.2mS
Correction period
Count value clearing
"0000010B"(former value
"0000000B"+1)