HD404318 Datasheet, PDF (41/66 Pages) Hitachi Semiconductor – 4-bit HMCS400-series microcomputer

HD404318 Series
Alarm Output Function
The MCU has an alarm output function built in. By setting port mode register C (PMRC: $025), one of
four alarm frequencies supplied from the PSS can be selected.
Table 9 Port Mode Register C
PMRC
Bit 3
0
1
Bit 2
0
1
0
1
System Clock Divisor
÷ 2048
÷ 1024
÷ 512
÷ 256
BUZZ
Alarm output
controller
Alarm output
control signal
Port mode
register A
(PMRA)
Selector
2
System ^øPER
clock
Prescaler S (PSS)
Port mode
register C
(PMRC)
Figure 32 Alarm Output Function Block Diagram
41