HD6433044 Hitachi Semiconductor, HD6433044 Datasheet - Page 194

• Manufacturer Part Number: HD6433044
• Description: (HD64 Series) Hitachi Single-Chip Microcomputer
• Manufacturer: Hitachi Semiconductor

Contention between RTCOR Write and Compare Match: If a compare match occurs in the T
state of an RTCOR write cycle, writing takes priority and the compare match signal is inhibited.
See figure 7-22.
RTCNT Operation at Internal Clock Source Switchover: Switching internal clock sources may
cause RTCNT to increment, depending on the switchover timing. Table 7-9 shows the relation
between the time of the switchover (by writing to bits CKS2 to CKS0) and the operation of
RTCNT.
The RTCNT input clock is generated from the internal clock source by detecting the falling edge
of the internal clock. If a switchover is made from a high clock source to a low clock source, as in
case No. 3 in table 7-9, the switchover will be regarded as a falling edge, an RTCNT clock pulse
will be generated, and RTCNT will be incremented.
Figure 7-22 Contention between RTCOR Write and Compare Match
ø
Address bus
Internal
write signal
RTCNT
RTCOR
Compare
match signal
RTCOR write cycle by CPU
T
1
RTCNT address
180
N
N
T
2
RTCOR write data
T
3
N + 1
Inhibited
M
3