Buzzer Function - Abov MC80F0304 User Manual

MC80F0304/08/16

17. BUZZER FUNCTION

The buzzer driver block consists of 6-bit binary counter, buzzer driving.
wave which has very wide range frequency (488Hz ~ 250kHz at register BUZR, and clock source selector. It generates square- Equation of frequency calculation is shown below.
XIN f = 4MHz) by user software. XIN f
A 50% duty pulse can be output to R12 / BUZO pin to use for pi- f BUZ = 2 -------------------------------------------------------------------------------- - × DivideRatio BUR × ( 1 + )
ezo-electric buzzer drive. Pin R12 is assigned for output port of
For PSR1 register, refer to Figure 17-2 . Buzzer driver by setting the bit 2 of PSR1(address 0F9 ) to "1". H f BUZ : Buzzer frequency
Example: 5kHz output at 4MHz. Divide Ratio: Prescaler divide ratio by BUCK[1:0] f XIN : Oscillator frequency
BUR: Lower 6-bit value of BUZR. Buzzer period value.
LDM LDM BUZR,#0011_0001B PSR1,#XXXX_X1XXB The frequency of output signal is controlled by the buzzer control
X means don't care quency for buzzer driving. register BUZR. The bit 0 to bit 5 of BUZR determine output fre-
The bit 0 to 5 of BUZR determines output frequency for buzzer
R12 port data
÷ 8 00 6-BIT BINARY
X PIN ÷ 16 01 COUNTER MUX
IN ÷ 32 10 0 R12/BUZO PIN
÷ 64 11 F/F 1
MUX 2 Comparator
Compare data BUZO
6 PSR1 Port selection register 1
BUR [0F9 H ]
[0E0 H ]
Internal bus line
Figure 17-1 Block Diagram of Buzzer Driver
RESET VALUE: 0FF ADDRESS: 0E0 H H ADDRESS: 0F9 H
W W W W W W W W RESET VALUE: ---- 0000 B
BUZR BUCK1 BUCK0 PSR1 - - - - - BUZO - -
Buzzer Period Data BUR[5:0] 0: R12 port (Turn off buzzer) R12 / BUZO Selection
Source clock select 1: BUZO port (Turn on buzzer)
01: f 00: f XIN XIN ÷ 16 ÷ 8
11: f 10: f XIN ÷ 64 ÷ 32
XIN
Figure 17-2 Buzzer Register & PSR1
92 November 4, 2011 Ver 2.12