M32C83T datasheet(179/527 Pages) RENESAS

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14. Timer (Timer B)

)

(

14.2.2 Event Counter Mode

In event counter mode, the timer counts how many external signals are applied or how many times

another timer overflows and underflows. (See Table 14.10) Figure 14.21 shows the TBiMR register (i=0

to 5) in event counter mode.

Table 14.10 Specifications in Event Counter Mode

Item

Specification

Count Source

• External signal applied to the TBiIN pin (i = 0 to 5) (valid edge can be selected by

program)

• TBj overflows or underflows (j=i-1, except j=2 when i=0, j=5 when i=3)

Counting Operation

• The timer decrements a counter value

When the timer counter underflows, content of the reload register is reloaded into the

count register to continue counting

Divide Ratio

1/(n+1)

n : setting value of the TBi register

000016 to FFFF16

Counter Start Condition

The TBiS bit 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 The timer counter underflows

TBiIN Pin Function

Programmable I/O port or count source input

Read from Timer

The TBi register indicates the value of the counter

Write to Timer

• When the timer counter stops,

the value written to the TBi register is also written to both reload register and counter

• While counting,

the value written to the TBi register is written to the reload register

(It is transferred to the counter at the next reload timing)

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