HD64F2149 Datasheet, PDF (352/1035 Pages) Renesas Technology Corp – Hitachi 16-Bit Single-Chip Microcomputer

When ICRC or ICRD is used as a buffer register, its input capture flag is set by the selected
transition of its input capture signal. For example, if ICRC is used to buffer ICRA, when the edge
transition selected by the IEDGC bit occurs on the FTIC input capture line, ICFC will be set, and
if the ICIEC bit is set, an interrupt will be requested. The FRC value will not be transferred to
ICRC, however.
In buffered input capture, if the upper byte of either of the two registers to which data will be
transferred (ICRA and ICRC, or ICRB and ICRD) is being read when the input signal arrives,
input capture is delayed by one system clock (ø) period. Figure 11.10 shows the timing when
BUFEA = 1.
Read cycle:
CPU reads ICRA or ICRC
T₁
T₂
ø
FTIA
Input capture
signal
Figure 11.10 Buffered Input Capture Timing (Input Capture Input when ICRA or ICRC is
Read)
11.3.5 Timing of Input Capture Flag (ICF) Setting
The input capture flag ICFx (x = A, B, C, D) is set to 1 by the internal input capture signal. The
FRC value is simultaneously transferred to the corresponding input capture register (ICRx). Figure
11.11 shows the timing of this operation.
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