HMS87C1808B Datasheet, PDF (59/99 Pages) List of Unclassifed Manufacturers – 8-BIT SINGLE-CHIP MICROCONTROLLERS

HMS87C1X04B/08B/16B
14. Buzzer Output function
The buzzer driver consists of 6-bit binary counter, the buzzer reg-
ister 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 setting the
bit BUZO of RBFUNC to “1”.
The 6-bit buzzer counter is cleared and start the counting by writ-
ing 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.
f_BUZ(Hz)
=
---------------^O----^s---^c---ⁱ--^l-^l-^a----^t-^o----^r---^F----^r--^e---^q----^u---^e---ⁿ----^c---^y---------------
2 × Prescaler Ratio × (BUR + 1)
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 : 1111_1111
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 14-1 Buzzer Driver
SEP. 2004 Ver 1.03
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