M32CSLASH8A datasheet(192/372 Pages) RENESAS

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M32C/8A Group

15. Timers (Timer B)

Rev.1.00

Jul 15, 2007

Page 175 of 352

REJ09B0385-0100

15.2.3

Pulse Period Measurement Mode, Pulse Width Measurement Mode

In pulse period measurement mode and pulse width measurement mode, the timer measures pulse period or

pulse width of the external signal.

Table 15.11 shows specifications in pulse period measurement mode and pulse width measurement mode.

Figure 15.29 shows a pulse period measurement operation. Figure 15.30 shows a pulse width measurement

operation.

Table 15.11

Specifications of Pulse Period Measurement Mode, Pulse Width Measurement Mode

NOTES:

1. Bits CNT3 to CNT0 in the TCSPR register select no division (n = 0) or divide-by-2n (n = 1 to 15).

2. An interrupt request is not generated when the first valid edge is input after the count starts.

3. To set the MR3 bit to 0 (no overflow), wait for one or more count source cycles to write to the TBiMR register

after the MR3 bit becomes 1, while the TBiS bit is set to 1.

4. A value read from the TBi register is undefined until the second valid edge is detected after the count starts.

Item

Specification

Count source

f1, f8, f2n(1), fC32

Count operation

• Counter increments

The counter value is transferred to the reload register when the valid edge of a

pulse is detected. Then the counter becomes 0000h and the

count continues.

Count start condition

The TBiS bit (i = 0 to 5) in the TABSR or TBSR register is set to 1 (count starts)

Count stop condition

The TBiS bit is set to 0 (count stops)

Interrupt request generation timing • When the valid edge of a pulse is input(2)

• When the timer overflows(3)

The MR3 bit in the TBiMR register is set to 1 (overflow) simultaneously.

TBiIN pin function

Pulse input

Read from timer

A read from the TBi register returns the contents of the reload register

(measurement results)(4)

Write to timer

The TBi register cannot be written

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