GMS81C2020 Datasheet, PDF (62/92 Pages) Hynix Semiconductor – CMOS Single-Chip 8-Bit Microcontroller with A/D Converter & VFD Driver

GMS81C2020/GMS81C2120
Hyundai Micro Electro nics
17. Buzzer Output function
The buzzer driver consists of 6-bit binary counter, the
buzzer register BUR and the clock selector. It generates
square-wave which is very wide range frequency (480
Hz~250 KHz at fxin = 4 MHz) by user programmable
counter.
Pin R03 is assigned for output port of Buzzer driver by set-
ting the bit BUZO of R0FUNC to "1".
The 6-bit buzzer counter is cleared and start the counting
by writing signal to the register BUR. It is increased from
00H until it matches 6-bit register BUR.
Also, it is cleared by counter overflow and count up to
output the square wave pulse of duty 50%.
The bit 0 to 5 of BUR determines output frequency for
buzzer driving. Frequency calculation is following as
shown below.

_()
=
----------------^O-----^s---^c---ⁱ-^l-^l--^a---^t--^o---^r----^F---^r--^e----^q---^u---^e----ⁿ---^c---^y-----------------
 × Prescaler Ratio × ( + )
The bits BUCK1, BUCK0 of BUR selects the source clock
from prescaler output.
BUR
BUCK1 BUCK0 BUR5 BUR4 BUR3 BUR2 BUR1 BUR0
Input clock selection
00 : fXI ÷ 8
01 : fXI ÷ 16
10 : fXI ÷ 32
11 : fXI ÷ 64
Buzzer Period Data
ADDRESS : DEH
RESET VALUE : 11111111
Bit Manipulation Not Available
÷8
÷ 16
fXI
÷ 32
MUX
÷ 64
BUCK[1:0]
Counter ( 6-bit )
BUR ( 6-bit )
Overflow
Detector
F/F
Writing to
BUR[5:0]
RESET
BUZO
[R0FUNC.3]
R03/BUZO
Figure 17-1 Buzzer Driver
62
preliminary
Nov. 1999 Ver 0.0