MC80F0424 Datasheet, PDF (92/135 Pages) List of Unclassifed Manufacturers – 8-BIT SINGLE-CHIP MICROCONTROLLERS

MC80F0424/0432/0448
Preliminary
18. BUZZER FUNCTION
The buzzer driver block consists of 6-bit binary counter, buzzer
register BUZR, and clock source selector. It generates 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 pi-
ezo-electric buzzer drive. Pin R13 is assigned for output port of
Buzzer driver by setting the bit 2 of PSR1(address 0F9_H) to “1”.
For PSR1 register, refer to Figure 10-3.
Example: 5kHz output at 4MHz.
LDM BUZR,#0011_0001B
LDM PSR1,#XXXX_X1XXB
X means don’t care
The bit 0 to 5 of BUZR determines output frequency for buzzer
driving.
Equation of frequency calculation is shown below.
f_BUZ
=
---------------------------------^f--^X----^I--^N----------------------------------
2 × DivideRatio × (BUR + 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 determine output fre-
quency 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
R13/BUZO PIN
1
BUZO
PSR1 Port selection register 1
[0F9_H]
Figure 18-1 Block Diagram of Buzzer Driver
BUZR
W WW
BUCK1 BUCK0
ADDRESS: 0E0_H
Reset VALUE: 0FF_H
W W WW W
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
Figure 18-2 Buzzer Register
88
MAR. 2005 Ver 0.2