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CHAPTER 15 BUZZER OUTPUT
15.1 Overview of Buzzer Output
The buzzer output can select from seven different output frequencies (square waves)
and can be used for applications such as sounding a buzzer to confirm key input. The
function uses the same output pin as the remote control transmit output.
s Buzzer Output Function
The buzzer output function outputs a signal (square wave) suitable for applications such as
sounding a buzzer to confirm an operation.
For buzzer output, one of seven output frequencies can be selected, or the output disabled.
Four divide-by-n outputs are supplied from the timebase timer and three from the watch
prescaler, for selection as the buzzer output signal.
Note:
Since divided outputs of the timebase timer and timeclock prescaler are fed as the buzzer
output signal, the buzzer output will be affected when the signal source selected for it
(timebase timer or watch prescaler) is cleared.
Check:
Since the timebase timer stops when the main clock oscillator stops (during subclock mode),
do not select the divided output of the timebase timer as the buzzer output when subclock
mode is used.
Check:
Similarly, do not select the watch prescaler as the buzzer source in a chip in which the single
clock option is selected.
Table 15.1-1 "Output Frequency" lists the seven output frequencies (square waves) that can be
selected for the buzzer output function.
FCH: Main clock oscillation frequency
FCL: Subclock oscillation frequency
The frequencies enclosed in parentheses ( ) are for FCH = 4.2 MHz, and FCL = 32.768 kHz.
Table 15.1-1 Output Frequency
Clock supply source
Buzzer output cycle
Square wave output (Hz)
Timebase Timer
212/FCH
FCH/2
12 (1.025 kHz)
211/FCH
FCH/2
11 (2.051 kHz)
210/FCH
FCH/2
10 (4.102 kHz)
29/FCH
FCH/2
9 (8.203 kHz)
Watch Prescaler
25/FCL
FCL/2
5 (1.024 kHz)
24/FCL
FCL/2
4 (2.048 kHz)
23/FCL
FCL/2
3 (4.096 kHz)