Toshiba TC9314F Manual page 49

Buzzer Output (BUZR)
The buzzer output is used for such purposes as audible alarms or to issue confirmation beeps for key-presses
or tuning scan mode. The buzzer frequency can be set as desired. 50% duty waveform is output.
1. BUZR Data Port
The BUZR output can also be used as the OT1 output port. To switch the OT1 output to BUZR output,
set bits B0~B7 to a value of 2 or higher.
The BUZR output has a frequency of 75 kHz divided by 2 × n (n = B0~B7). The B0~B7 setting range and
frequency range is 2 < = n < = 255. This can be expressed as a formula as follows.
75 kHz
= 18.75
2 × 2
Set B0~B7 to 1 or 0 to use the pin for OT1 output. The output states are as follows.
B7 B6 B5 B4
0 0 0 0
0 0 0 0
To set the above data, use the OUT1 instruction with the operand [C
Note 53: After a system reset, the BUZR data port is reset to "0".
2. BUZR Circuit Structure
The buzzer circuit consists of an 8 bit programmable counter, a 1/2 counter, a buzzer latch, and a buzzer
data port.
3. BUZR Output Timing
75 kHz
< = ƒ < =
kHz
BUZR
2 × 255
B3 B2 B1 B0
0 0 0 0
0 0 0 1
= 147 Ηz
OT1 Output
Low level output
High level output
49
TC9314F
= AH~BH].
N
2003-07-03