Table 2-7 Buzzer Output Frequencies (At 8.0 Mhz Of Oscillation Frequency) - Fujitsu MB89140 Series Hardware Manual

BUZZER OUTPUT
CIRCUIT
Address: 000E BUZR
H
HARDWARE CONFIGURATION
Description of Registers
The detail of buzzer register is described below.
Buzzer register (BUZR)
This 2-bit register enables buzzer output and selects the frequency.
Bit 7 Bit 6
— —
Address: 000E
H
[Bits 1 and 0] BUZ1, BUZ0: Buzzer-select bits
These bits are used to enable buzzer output and select the frequency. The
buzzer output function is disabled by 00. In other cases, the frequencies
listed in the table below are selected.
Table 2-7 Buzzer Output Frequencies
(at 8.0 MHz of oscillation frequency)
BUZ1 BUZ0
0 0
0 1
1 0
1 1
Description of Operation
This circuit outputs a signal for use as a check sound. The buzzer register is
used to enable buzzer output and select the frequency. Setting 00 at the
BUZR register produces a square wave of Hi-Z frequency, and setting 01
produces a square wave of High frequency.
Setting 10 or 11 at the BUZR register, and setting the square wave as above
values.
Precautions for Buzzer Output Circuit
Part of the time-base timer is used as the buzzer output. Therefore, clear
operation of the time-base timer affects the circuit.
2-84
Bit 5 Bit 4 Bit 3 Bit 2
— — — —
Buzzer output frequency
High impedance
Set (H)
3.91 kHz
1.95 kHz
Bit 1 Bit 0
BUZ1 BUZ0
(R/W) (R/W)
Initial value
------00
B