MC80F0204 Datasheet, PDF (82/126 Pages) List of Unclassifed Manufacturers – 8-BIT SINGLE-CHIP MICROCONTROLLERS

MC80F0104/0204
Preliminary
17. BUZZER FUNCTION
The buzzer driver block consists of 6-bit binary counter,
buzzer register BUZR, and clock source selector. It gener-
ates square-wave which has very wide range frequency
(488Hz ~ 250kHz at f_XIN= 4MHz) by user software.
A 50% duty pulse can be output to R13 / BUZO pin to use
for piezo-electric buzzer drive. Pin R13 is assigned for out-
put port of Buzzer driver by setting the bit 2 of PSR1(ad-
dress 0F9_H) to “1”. For PSR1 register, refer to Figure 17-2
.
Example: 5kHz output at 4MHz.
LDM
LDM
X means don’t care
BUZR,#0011_0001B
PSR1,#XXXX_X1XXB
The bit 0 to 5 of BUZR determines output frequency for
buzzer driving.
Equation of frequency calculation is shown below.
f_BUZ = -₂-----_×----_D-----_i--_v----_i--_d----_e----_R----_af---^X-_t--_i^I--^N_o-----_×-----₍--_B-----_U-----_R------+-----₁----₎
f_BUZ: Buzzer frequency
f_XIN: Oscillator frequency
Divide Ratio: Prescaler divide ratio by BUCK[1:0]
BUR: Lower 6-bit value of BUZR. Buzzer period value.
The frequency of output signal is controlled by the buzzer
control register BUZR. The bit 0 to bit 5 of BUZR deter-
mine output frequency for buzzer driving.
X_IN PIN
÷8
00
÷ 16
01
÷ 32
10
÷ 64 ₁₁
MUX
2
[0E0_H]
R13 port data
6-BIT BINARY
COUNTER
F/F
Comparator
Compare data
6
BUR
Internal bus line
MUX
0
R12/BUZO PIN
1
BUZO
PSR1 Port selection register 1
[0F9_H]
Figure 17-1 Block Diagram of Buzzer Driver
BUZR
WW
ADDRESS: 0E0_H
RESET VALUE: 0FF_H
WWWW WW
BUCK1 BUCK0
BUR[5:0]
Buzzer Period Data
Source clock select
00: f_XIN ÷ 8
01: f_XIN ÷ 16
10: f_XIN ÷ 32
11: f_XIN ÷ 64
ADDRESS: 0F9_H
RESET VALUE: ---- 0000_B
PSR1 ^-
-
-
-
- BUZO -
-
R12 / BUZO Selection
0: R12 port (Turn off buzzer)
1: BUZO port (Turn on buzzer)
Figure 17-2 Buzzer Register & PSR1
78
Mar. 2005 Ver 0.2