Operation Timing; Tcnt Count Timing; Figure 12.14 Count Timing For Internal Clock Source; Figure 12.15 Count Timing For External Clock Source - Renesas H8 Series Hardware Manual

12.5

Operation Timing

12.5.1

TCNT Count Timing

Figure 12.14 shows the TCNT count timing when the internal clock source is selected. Figure
12.15 shows the timing when the external clock source is selected. The pulse width of the external
clock signal must be at least two system clock (φ) cycles; shorter pulses will not be counted
correctly.
φ
Internal
clock
TCNT input
clock
TCNT

Figure 12.14 Count Timing for Internal Clock Source

φ
External
clock
TCNT input
clock
TCNT

Figure 12.15 Count Timing for External Clock Source

Rising edge
N
Rising edge
N
N+1
Rising edge
N+1
Rev. 3.00 Sep. 14, 2006 Page 181 of 408
Section 12 Timer W
N+2
N+2
REJ09B0105-0300