HMS87C1304A Datasheet, PDF (45/70 Pages) Hynix Semiconductor – CMOS SINGLE-CHIP 8-BIT MICROCONTROLLER

HYUNDAI MicroElectronics
HMS87C1304A/HMS87C1302A
13. 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 RB1 is assigned for output port of Buzzer driver by set-
ting the bit BUZO of RBFUNC 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 out-
put 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
ADDRESS : DEH
RESET VALUE : 11111111
Bit Manipulation Not Available
fxin
Input clock selection
00 : fxin ÷ 8
01 : fxin ÷ 16
10 : fxin ÷ 32
11 : fxin ÷ 64
÷8
÷ 16
÷ 32
MUX
÷ 64
BUCK[1:0]
Buzzer Period Data
inary _{COUNTER (6-bit)}
Prelim ^{BUR (6-bit)}
F/F
COMPARATOR
BUZO
[RBFUNC.1]
RB1/BUZ PIN
Figure 13-1 Buzzer Driver
Jan. 2001
Preliminary
45