Hitachi H8/329 Series Hardware Manual page 140

Ø
Internal
clock
FRC clock
pulse
FRC N – 1
Figure 6-5. Increment Timing for Internal Clock Source
External Clock: If external clock input is selected, the FRC increments on the rising edge of the
FTCI clock signal. Figure 6-6 shows the increment timing.
The pulse width of the external clock signal must be at least 1.5 system clock (Ø) periods. The
counter will not increment correctly if the pulse width is shorter than 1.5 system clock periods.
Ø
FTCI
FRC clock pulse
FRC
Figure 6-6. Increment Timing for External Clock Source
Ø
FTCI
N
Figure 6-7. Minimum External Clock Pulse Width
N
131
N + 1
N + 1