GMS81C2012 datasheet(69/107 Pages) HYNIX

69 / 107 page

HYUNDAI MicroElectronics

GMS81C2012/GMS81C2020

MAR. 2000 Ver 1.00

15. BUZZER FUNCTION

The buzzer driver block consists of 6-bit binary counter,

buzzer register BUR, and clock source selector. It gener-

ates square-wave which has very wide range frequency

(480Hz ~ 250kHz at fXIN= 4MHz) by user software.

A 50% duty pulse can be output to R03/BUZO pin to use

for piezo-electric buzzer drive. Pin R03 is assigned for output

port of Buzzer driver by setting the bit 3 of R0FUNC(address

0F4H) to “1”. At this time, the pin R03 must be defined as

output mode (the bit 3 of R0IO=1).

Example: 5kHz output at 4MHz.

LDM

R0IO,#XXXX_1XXXB

LDM

BUR,#0011_0010B

LDM

R0FUNC,#XXXX_1XXXB

X means don’t care

The bit 0 to 5 of BUR determines output frequency for

buzzer driving.

Equation of frequency calculation is shown below.

fBUZ: Buzzer frequency

fXIN: Oscillator frequency

Divide Ratio: Prescaler divide ratio by BUCK[1:0]

BUR: Lower 6-bit value of BUR. Buzzer period value.

The frequency of output signal is controlled by the buzzer

control register BUR.The bit 0 to bit 5 of BUR determine

output frequency for buzzer driving.

Figure 15-1 Block Diagram of Buzzer Driver

Figure 15-2 R0FUNC and Buzzer Register

BUZ

XIN

DivideRatio

BUR

()

----------------------------------------------------------------------------

÷8

÷32

÷16

÷64

BUR

R03/BUZO PIN

R0FUNC

Internal bus line

R03 port data

XIN PIN

6-bit binary

[0DEH]

[0F4H]

F/F

÷2

Comparator

Compare data

6-BIT COUNTER

MUX

Port selection

BUR[5:0]

BUR

ADDRESS: 0DEH

RESET VALUE: Undefined

Source clock select

00:

÷ 8

01:

÷ 16

10:

÷ 32

11:

÷ 64

Buzzer Period Data

R03/BUZO Selection

R0FUNC

ADDRESS : 0F4H

RESET VALUE : ---- 0000B

0: R03 port (Turn off buzzer)

1: BUZO port (Turn on buzzer)

BUCK1 BUCK0

BUZO

EC0

INT1

INT0

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