HD64F3694FXV Datasheet, PDF (198/452 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

Section 12 Timer W
The TCNT value can be captured into a general register (GRA, GRB, GRC, or GRD) when a
signal level changes at an input-capture pin (FTIOA, FTIOB, FTIOC, or FTIOD). Capture can
take place on the rising edge, falling edge, or both edges. By using the input-capture function, the
pulse width and periods can be measured. Figure 12.7 shows an example of input capture when
both edges of FTIOA and the falling edge of FTIOB are selected as capture edges. TCNT operates
as a free-running counter.
TCNT value
H'FFFF
H'F000
H'AA55
H'55AA
H'1000
H'0000
FTIOA
GRA
H'1000
H'F000
Time
H'55AA
FTIOB
GRB
H'AA55
Figure 12.7 Input Capture Operating Example
Figure 12.8 shows an example of buffer operation when the GRA is set as an input-capture
register and GRC is set as the buffer register for GRA. TCNT operates as a free-running counter,
and FTIOA captures both rising and falling edge of the input signal. Due to the buffer operation,
the GRA value is transferred to GRC by input-capture A and the TCNT value is stored in GRA.
Rev.5.00 Nov. 02, 2005 Page 168 of 418
REJ09B0028-0500