HD64F2149 Datasheet, PDF (417/1035 Pages) Renesas Technology Corp – Hitachi 16-Bit Single-Chip Microcomputer

13.3.5 IVI Signal Fall Modification and IHI Synchronization
By using the timer connection TMR1, the fall of the IVI signal can be shifted backward by the
specified number of IHI signal waveforms. Also, the fall of the IVI signal can be synchronized
with the rise of the IHI signal.
To perform 8-bit timer divided waveform period measurement, TCNT in TMR1 is set to count
external clock (IHI signal) pulses, and to be cleared on the rising edge of the external reset signal
(inverse of the IVI signal). The number of IHI signal pulses until the fall of the IVI signal is
written in TCORB.
Since the IVI signal supplied to the IVO signal selection circuit is normally set on the rise of the
IVI signal and reset on the fall, its waveform is the same as that of the original IVI signal. When
fall modification is selected, a reset is performed on a TMR1 TCORB compare-match.
The fall of the waveform generated in this way can be synchronized with the rise of the IHI signal,
regardless of whether or not fall modification is selected.
Examples of TMR1 TCORB, TCR, and TCSR settings are shown in table 13.7, and the fall
modification/IHI synchronization timing chart is shown in figure 13.7.
Table 13.7 Examples of TCORB, TCR, and TCSR Settings
Register
Bit(s) Abbreviation Contents Description
TCR in
7
CMIEB
0
TMR1
Interrupts due to compare-match and
overflow are disabled
6
CMIEA
0
5
OVIE
0
4 and 3 CCLR1,
11
CCLR0
TCNT is cleared by the rising edge of the
external reset signal (inverse of the IVI
signal)
2 to 0 CKS2 to CKS0 101
TCNT is incremented on the rising edge of
the external clock (IHI signal)
TCSR in
TMR1
3 to 0 OS3 to OS0 0011
Not changed by compare-match B; output
inverted by compare-match A (toggle
output)
1001
or
when TCORB ≤ TCORA, 1 output on
compare-match B, 0 output on compare-
match A
TCORB in TMR1
H'03
Compare-match on the 4th (example) rise
(example) of the IHI signal after the rise of the
inverse of the IVI signal
383