HD6413308 Hitachi Semiconductor, HD6413308 Datasheet - Page 164

• Manufacturer Part Number: HD6413308
• Description: Hitachi Single-Chip MicroComputer
• Manufacturer: Hitachi Semiconductor

(4) Incrementation Caused by Changing of Internal Clock Source: When an internal clock
source is changed, the changeover may cause the FRC to increment. This depends on the time at
which the clock select bits (CKS1 and CKS0) are rewritten, as shown in Table 6-4.
The pulse that increments the FRC is generated at the falling edge of the internal clock source. If
clock sources are changed when the old source is High and the new source is Low, as in case No. 3
in Table 6-5, the changeover generates a falling edge that triggers the FRC increment clock pulse.
Switching between an internal and external clock source can also cause the FRC to increment.
Figure 6-23. Contention between OCR Write and Compare-Match
Internal address bus
Internal write signal
FRC
OCRA or OCRB
Compare-match
A or B signal
Ø
Write cycle: CPU write to lower byte of OCRA or OCRB
T
1
N
N
149
OCR address
T
2
Write data
T
3
N + 1
M
Inhibited