GMS81C1404 Datasheet, PDF (55/93 Pages) Hynix Semiconductor – 8-BIT SINGLE-CHIP MICROCONTROLLERS

GMS81C1404/GMS81C1408
15. 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.
_i|(o¡) = _Y------_×----_P----_r--^Oe----_s-^s--_c-^c--_a-ⁱ-^l-_ll-_e-^a---_rt--^o-_R--^r---_a-^F--_t-^r-_i-_oe----^q-_×--^u---₍^e--_i--ⁿ---_|^c---^y--_y-----+-----_X-----₎
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 : fxin ÷ 8
01 : fxin ÷ 16
10 : fxin ÷ 32
11 : fxin ÷ 64
Buzzer Period Data
ADDRESS : DEH
RESET VALUE : 11111111
Bit Manipulation Not Available
÷8
÷ 16
fxin
÷ 32
MUX
÷ 64
BUCK[1:0]
COUNTER (6-bit)
BUR (6-bit)
F/F
COMPARATOR
BUZO
[RBFUNC.1]
RB1/BUZ PIN
Figure 15-1 Buzzer Driver
June. 2001 Ver 1.2
53