Counting Timing Of The Frc - Renesas Hitachi H8S/2194 Series Hardware Manual

17.3.2

Counting Timing of the FRC

The FRC is counted up by the inputting clock. By setting the CKS1 and CKS0 of the TCRX, the
inputting clock can be selected from among three different types of clocks (φ/4, φ/16 and φ/64)
and the DVCFG.
(1) In Case of Internal Clock Operation
By setting the CKS1 and CKS0 bits of the TCRX, three types of internal clocks (φ/4, φ/16
and φ/64), generated by dividing the system clock (φ) can be selected. Figure 17.3 shows the
timing chart at this time.
Internal clock
FRC input
clock
FRC
Figure 17.3 Count Timing in Case of Internal Clock Operation
(2) In Case of DVCFG Clock Operation
By setting the CKS1 and CKS0 bits of the TCRX to 1, DVCFG clock input can be selected.
The DVCFG clock makes counting by use of the edge detecting pulse being selected by the
CFG dividing timer.
Figure 17.4 shows the timing chart at this time.
CFG
DVCFG
FRC input
clock
FRC
Figure 17.4 Count Timing in Case of CFG Clock Operation
N-1 N
N
Rev. 2.0, 11/00, page 377 of 1037
N+1
N+1