Renesas 4514 User Manual
APPLICATION
2.3 Timers
2-30
4513/4514 Group User’s Manual
2.3.3 Timer application examples
(1)
Timer operation: measurement of constant period
The constant period by the setting timer count value can be measured.
The constant period by the setting timer count value can be measured.
Outline: The constant period by the timer 1 underflow signal can be measured.
Specifications: Timer 1 and prescaler divides the system clock frequency f(X
Specifications: Timer 1 and prescaler divides the system clock frequency f(X
IN
) = 4.0 MHz, and the
timer 1 interrupt request occurs every 3 ms.
Figure 2.3.3 shows the setting example of the constant period measurement.
(2)
CNTR0 output operation: piezoelectric buzzer output
Outline: Square wave output from timer 1 can be used for piezoelectric buzzer output.
Specifications: 4 kHz square wave is output from the CNTR0 pin at system clock frequency f(X
Specifications: 4 kHz square wave is output from the CNTR0 pin at system clock frequency f(X
IN
)
= 4.0 MHz. Also, timer 1 interrupt occurs simultaneously.
Figure 2.3.1 shows the peripheral circuit example, and Figure 2.3.4 shows the setting example of
CNTR0 output.
CNTR0 output.
Fig. 2.3.1 Peripheral circuit example
(3)
CNTR0 input operation: event count
Outline: Count operation can be performed by using the signal (rising waveform) input from CNTR0
pin as the event.
Specifications: The low-frequency pulse from external as the timer 2 count source is input to CNTR0
pin, and the timer 2 interrupt request occurs every 100 counts.
Figure 2.3.5 shows the setting example of CNTR0 input.
4513/4514
CNTR0
125
µ
s125
µ
s
Set dividing ratio for timer 1 underflow cycle to 125
µ
s.
In order to reduce the current dissipation,
output is high-impedance state during buzzer
output stop.
output is high-impedance state during buzzer
output stop.