King Billion Electronics Co., Ltd.
HE89C21
駿 億 電 子 股 份 有 限 公 司
HE80000 SERIES
8.Oscillators
The MCU is equipped with two clock sources with a variety of selections on the types of oscillators to
choose from. So that system designer can select oscillator types based on the cost target, timing accuracy
requirements etc. With two clock sources available, the system can switch among operation modes of Fast,
Slow, Idle, and Sleep modes by the setting of OP1 and OP2 registers as shown in tables below to suit the
needs of application such as power saving, etc.
OP1
Field
Mode
Reset
Bit 7
Bit 6
Bit 5
Bit 4
INTE
R/W
0
Bit 3
T2E
R/W
0
Bit 2
T1E
R/W
0
Bit 1
Z
R/W
-
Bit 0
C
R/W
-
1
R
1
STOP SLOW
R/W
0
R/W
0
OP2
Field
Mode
Reset
Bit 7
Bit 6
Bit 5
Bit 4
TBE
R/W
0
Bit 3
Bit 2
Bit 1
Bit 0
IDLE PNWK TCWK
TBS[3..0]
R/W
0
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
Crystal, Resonator or RC oscillator can be used as fast clock source. External components should be
placed as close to the oscillator pins as possible. The type of oscillator used is selected by mask option
MO_FXTAL.
MO_FXTAL Fast clock type
0
1
RC Oscillator.
Crystal Oscillator.
VDD
FXI
R
FXI
C
FXO
Slow clock is clock source for LCD display, Timer1, and Timer Base, etc. Crystal oscillator can be used
as slow clock. If used in feature phone applications, 32768 Hz crystal is suggested to generate DTMF
tone.
January 20, 2003
7
V1.0E
KB [ King blillion Electronics Co.,Ltd. ]
