p2125vps20 Renesas Electronics Corporation., p2125vps20 Datasheet - Page 291

• Manufacturer Part Number: p2125vps20
• Description: 16-bit Single-chip Microcomputer H8s Family / H8s/2100 Series
• Manufacturer: Renesas Electronics Corporation.

12.4
TCMCNT operates in timer mode or speed measurement mode. TCMCNT is in timer mode after a
reset.
12.4.1
(1)
TCMCNT operates as a free running counter in timer mode. TCMCNT starts counting up when
the CST bit in TCMCR is set to 1. When TCMCNT overflows (the value changes from H'FFFF to
H'0000), the OVF bit in TCMCSR is set to 1 and an interrupt request is generated if the OVIE bit
in TCMIER is 1. Figure 12.2 shows an example of free running counter operation. In addition,
figure 12.3 shows TCMCNT count timing of external clock operation. The external clock should
have a pulse width of no less than 1.5 cycles. The counter will not operate correctly if the pulses
are narrower than this.
φ
φ/4
TCMCNT
input clock
TCMCNT
φ
External clock
TCMCNT
input clock
TCMCNT
Counter Operation
Operation
Timer Mode
Figure 12.3 Count Timing of External Clock Operation (Falling Edges)
Figure 12.2 Example of Free Running Counter Operation
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Section 12 16-Bit Cycle Measurement Timer (TCM)
Rev. 1.00 Sep. 21, 2006 Page 253 of 658
N
N
REJ09B0310-0100
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