7906 Datasheet, PDF (171/531 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER

TIMER B
8.5 Pulse period/Pulse width measurement mode
Table 8.5.2 Specifications of pulse period/pulse width measurement mode (when free-run type is selected)
Item
Specifications
Count source fi
Count operation
f2, f16, f64, or f512
q Countup
q Counter value is transferred to the reload register at valid edge of
measurement pulse, and counting continues.
q When a counter overflow occurs, the timer Bi overflow flag is set to
Count start condition
“1,” and counting continues after clearing the counter value to “000016.”
When the count start bit is set to “1.”
Count stop condition
When the count start bit is cleared to “0.”
Interrupt request occurrence timing When a valid edge of measurement pulse is input (Note 1).
TBiIN pin’s function
Read from timer Bi register
Measurement pulse input pin (Note 2)
The value obtained by reading the timer Bi register is the reload
register’s contents (Measurement result) (Note 3).
Write to timer Bi register
Invalid
Timer Bi overflow flag: This bit is used to identify the source of an interrupt request occurrence.
Notes 1: No interrupt request occurs when the first valid edge is input after the counter starts counting.
2: When using timer B2, make sure that the timer B2 clock source select bit (see Figure 8.4.2.) =
“0.”
3: The value read out from the timer Bi register is undefined in the period after the counter starts
counting until the second valid edge is input.
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7906 Group User’s Manual Rev.2.0