Pulse Period/Pulse Width Measurement Mode - Renesas 7700 FAMILY User Manual

6.5 Pulse period/pulse width measurement mode

In these mode, the timer measures an external signal's pulse period or pulse width. (Refer to Table 6.5.1.)
Figure 6.5.1 shows the structures of the timer Bi mode register and timer Bi register in the pulse period/
pulse width measurement mode.
Pulse period measurement
The timer measures the pulse period of the external signal that is input to the TBi
Pulse width measurement
The timer measures the pulse width ("L" level and "H" level widths) of the external signal that is input
to the TBi pin.
IN
Table 6.5.1 Specifications of pulse period/pulse width measurement mode
Item
Count source
Count operation
Count start condition
Count stop condition
Interrupt request occurrence timing
TBi pin function
IN
Read from timer Bi register
Write to timer Bi register
Timer Bi overflow flag : The bit used to identify the source of an interrupt request occurrence.
Notes 1: This interrupt request does not occur when the first valid edge is input after the timer starts
counting.
2: The value read out from the timer Bi register is undefined until the second valid edge is input after
the timer starts counting.
6.5 Pulse period/pulse width measurement mode
f /f , f /f , f /f , or f
2 4 16 32 64 128
Up-count
Counter value is transferred to reload register at valid edge of mea-
surement pulse, and counting continues after clearing the counter
value to "0000 ."
16
When count start bit is set to "1."
When count start bit is cleared to "0."
When valid edge of measurement pulse is input (Note 1).
When counter overflows (Timer Bi overflow flag is set to "1" simultaneously).
Measurement pulse input
The value got by reading timer Bi register is the reload register's
contents, measurement result (Note 2).
Impossible.
7751 Group User's Manual
Specifications
/f
512 1024
TIMER B
pin.
IN
6–19