Datasheet

Section 11 16-Bit Free-Running Timer (FRT)
Rev. 3.00 Mar 21, 2006 page 274 of 788
REJ09B0300-0300
11.5.4 Input Capture Input Timing
The rising or falling edge can be selected for the input capture input timing by the IEDGA to
IEDGD bits in TCR. Figure 11.7 shows the usual input capture timing when the rising edge is
selected.
φ
Input capture
input pin
Input capture signal
Figure 11.7 Input Capture Input Signal Timing (Usual Case)
If ICRA to ICRAD are read when the corresponding input capture signal arrives, the internal input
capture signal is delayed by one system clock (φ). Figure 11.8 shows the timing for this case.
T
1
T
2
Read cycle of ICRA to ICRD
φ
Input capture
input pin
Input capture signal
Figure 11.8 Input Capture Input Signal Timing (When ICRA to ICRD are Read)
11.5.5 Buffered Input Capture Input Timing
ICRC and ICRD can operate as buffers for ICRA and ICRB, respectively. Figure 11.9 shows how
input capture operates when ICRC is used as ICRA's buffer register (BUFEA = 1) and IEDGA and
IEDGC are set to different values (IEDGA = 0 and IEDGC = 1, or IEDGA = 1 and IEDGC = 0),
so that input capture is performed on both the rising and falling edges of FTIA.