Datasheet

Section 12 Timer Z
Rev. 4.00 Mar. 15, 2006 Page 190 of 556
REJ09B0026-0400
• External clock operation
An external clock input pin (TCLK) can be selected by bits TPSC2 to TPSC0 in TCR, and a
detection edge can be selected by bits CKEG1 and CKEG0. To detect an external clock, the
rising edge, falling edge, or both edges can be selected. The pulse width of the external clock
needs two or more system clocks. Note that an external clock does not operate correctly with
the lower pulse width.
Figure 12.11 illustrates the detection timing of the rising and falling edges.
TCNT
External clock input pin
TCNT input
N-1 N N+1
φ
Figure 12.11 Count Timing at External Clock Operation (Both Edges Detected)