3850 datasheet(91/261 Pages) RENESAS

tên linh kiện	3850

Giải thích chi tiết về linh kiện	8-BIT SINGLE-CHIP MICROCOMPUTER

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2-22

3850/3851 Group User’s Manual

APPLICATION

2.2 Timer

(5) Timer application example 4: Measurement of FG pulse width for motor

Outline: The timer X counts the “H” level width of the pulses input to the P27/CNTR0 pin. An

underflow is detected by the timer X interrupt and an end of the input pulse “H” level is

detected by the CNTR0 interrupt.

Specifications: •The timer X counts the “H” level width of the FG pulse input to the P27/CNTR0 pin.

When the clock frequency is 4.19 MHz, the count source is 3.8

µs, which is obtained by dividing

the clock frequency by 16. Measurement can be made up to 250 ms in the range of FFFF16 to

000016.

Figure 2.2.21 shows the timers connection and setting of division ratio; Figure 2.2.22 shows the

relevant registers setting; Figure 2.2.23 shows the control procedure.

Fig. 2.2.21 Timers connection and setting of division ratios

250 ms

1/16

1/256

f(XIN) = 4.19 MHz

Timer X count source

selection bit

Prescaler X

Timer X

Timer X interrupt

request bit

0 : No interrupt request issued

1 : Interrupt request issued

0 or 1

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