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4.13.4 I/O memory of buzzer output circuit
Table 4.13.4.1 shows the I/O address and the control bits for the buzzer output circuit.
Register
Address
D3
D2
0
ENON
BZFQ
FF64H
R
*1 Initial value at initial reset
*2 Not set in the circuit
*3 Constantly "0" when being read
ENON: Interval ON/OFF control register (FF64H•D2)
Controls the addition of a 2 Hz interval onto the buzzer signal.
When "1" is written: ON
When "0" is written: OFF
Reading: Valid
Writing "1" into the ENON causes a 2 Hz ON/OFF interval to be added during buzzer signal output.
When "0" has been written, a 2 Hz ON/OFF interval is not added.
At initial reset, this register is set to "0".
BZFQ: Buzzer frequency selection register (FF64H•D1)
Selects the buzzer signal frequency.
When "1" is written: 2 kHz
When "0" is written: 4 kHz
Reading: Valid
When "1" is written to BZFQ, the frequency is set to 2 kHz. When "0" is written, it is set to 4 kHz.
At initial reset, this register is set to "0".
BZON: Buzzer output control (ON/OFF) register (FF64H•D0)
Controls the buzzer signal output.
When "1" is written: Buzzer output ON
When "0" is written: Buzzer output OFF
Reading: Valid
When "1" is written to BZON, the buzzer signal is output from the BZ terminal. When "0" is written, the
BZ terminal goes to a high (V
(V
) level (when positive polarity is selected by mask option).
SS
At initial reset, this register is set to "0".
4.13.5 Programming note
Since it generates a buzzer signal that is out of synchronization with the BZON register, hazards may at
times be produced when the signal goes ON/OFF due to the setting of the BZON register.
S1C63358 TECHNICAL MANUAL
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Buzzer Output Circuit)
Table 4.13.4.1 Control bits of buzzer output circuit
∗1
D1
D0
Name Init
∗3
∗2
0
–
BZON
ENON
0
BZFQ
0
R/W
BZON
0
) level (when negative polarity is selected by mask option) or to a low
DD
1
0
Unused
On
Off
2 Hz interval On/Off
2 kHz
4 kHz
Buzzer frequency selection
On
Off
Buzzer output On/Off
EPSON
Comment
103
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