M32C83T datasheet(181/527 Pages) RENESAS

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14. Timer (Timer B)

)

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14.2.3 Pulse Period/Pulse Width Measurement Mode

In pulse period/pulse width measurement mode, the timer measures pulse period or pulse width of an

external signal. (See Table 14.11) Figure 14.22 shows the TBiMR register (i=0 to 5) in pulse period/pulse

width measurement mode. Figure 14.23 shows an example of an operation timing when measuring a

pulse period. Figure 14.24 shows an example of the pulse width measurement.

Table 14.11 Specifications in Pulse Period/Pulse Width Measurement Mode

Item

Specification

Count Source

f1, f8, f2n(3), fC32

Counting Operation

• The timer increments a counter value

Counter value is transferred to the reload register on the valid edge of a pulse to be

measured. It is set to "000016" and the timer continues counting

Counter Start Condition

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

Counter Stop Condition

The TBiS bit is set to "0" (stops counting)

Interrupt Request Generation Timing • On the valid edge of a pulse to be measured(1)

• The timer counter overflows

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

TBiS bit is set to "1" (start counting) and the next count source is counted after setting

the MR3 bit to "1" (overflow), the MR3 bit can be set to "0" (no overflow) by writing to

the TBiMR register.

TBiIN Pin Function

Input for a pulse to be measured

Read from Timer

The TBi register indicates reload register values (measurement results)(2)

Write to Timer

Value written to the TBi register can be written to neither reload register nor counter

NOTES:

1. No interrupt request is generated when the pulse to be measured is on the first valid edge after the

timer has started counting.

2. The TBi register is in an indeterminate state until the pulse to be measured is on the second valid

edge after the timer has started counting.

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

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