上海贝岭股½有限公司
上海贝岭股½有限公司
Shanghai Belling Co., Ltd.
BL22P14 USER MANUAL
BM22P14 用户手册
01：
10：
Fs=Frtc
Fs=Fwdt
5.4.3 Crystal Oscillator
Crystal oscillator provides the clock of 455KHz-8MHz. A crystal should be connected
between the pin of OSC1 and OSC2.
Frequency of crystal
8MHz
4MHz
455KHz
Value of C1/C2
0/10p
0/10p/20p
100p/200p
5.4.4 External RC Oscillator
Using external RC oscillator, a resistor between OSC1 and VSS is required. The value of
resistor 800K ~40K , the frequency of clock will be 400KHz~8MHz. OSC2 can output
clock of Fsys if connecting a resistor from OSC2 to VDD. However, the frequency of
oscillator may vary with VDD, temperature and chip itself due to process variations. It is
therefore, not suitable for timing sensitive operations where accurate frequency is desired.
5.4.5 RTC Oscillator
RTC oscillator provides the clock of 32768Hz. A crystal should be connected between the
pin of OSC3 and OSC4. If it is the clock source of Fs, RTC oscillator will still work in stop
mode.
The RTC Oscillator circuit can be controlled to oscillate quickly by setting the “QOSC” bit
(bit 3 of register of MCR2). It is recommend to turn on the quick oscillating function upon
power on and then turn it off after 2 seconds.
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