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 f
i
f2, f16, f64, or f512
Count operation
✕ Countup
✕ Counter value is transferred to the reload register at valid edge of
measurement pulse, and counting continues.
✕ When a counter overflow occurs, the timer Bi overflow flag is set to
“1,” and counting continues after clearing the counter value to “000016.”
When the count start bit is set to “1.”
Count start condition
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
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).
Invalid
Read from timer Bi register
Write to timer Bi register
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.
7906 Group User’s Manual Rev.2.0
8-20
RENESAS [ RENESAS TECHNOLOGY CORP ]
