h8s-2138 Renesas Electronics Corporation., h8s-2138 Datasheet - Page 412

• Manufacturer Part Number: h8s-2138
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2100 Series
• Manufacturer: Renesas Electronics Corporation.

Section 13 Timer Connection [H8S/2138 Group]
13.3.3
The timer connection facility, TMR1, and the free-running timer (FRT) can be used to measure the
period of an IHI signal divided waveform. Since TMR1 can be cleared by a rising edge of inverted
IVI signal, the rise and fall of the IHI signal divided waveform can be virtually synchronized with
the IVI signal. This enables period measurement to be carried out efficiently.
To measure the period of an IHI signal divided waveform, TCNT in TMR1 is set to count the
external clock (IHI signal) pulses and to be cleared on the rising edge of the external reset signal
(inverted IVI signal). The value to be used as the division factor is written in TCORA, and the
TMO output method is specified by the OS bits in TCSR. Examples of TCR and TCSR settings
are shown in table 13.5, and the timing chart for measurement of the IVI signal and IHI signal
divided waveform periods is shown in figure 13.5. The period of the IHI signal divided waveform
is given by (ICRD(3) – ICRD(2))
Rev. 4.00 Jun 06, 2006 page 358 of 1004
REJ09B0301-0400
TICR+TCORC
Figure 13.3 Timing Chart for Clamp Waveform Generation (CL1 and CL2 Signals)
IHI signal
CL1 signal
CL2 signal
TCNT
TCORA
IHI signal
CL3 signal
TCNT
TICR
Figure 13.4 Timing Chart for Clamp Waveform Generation (CL3 Signal)
Measurement of 8-Bit Timer Divided Waveform Period
the resolution.