HT49R50 Holtek Semiconductor Inc, HT49R50 Datasheet - Page 18

• Manufacturer Part Number: HT49R50
• Description: 8-Bit Microcontroller
• Manufacturer: Holtek Semiconductor Inc

Time base
The time base offers a periodic time-out period
to generate a regular internal interrupt. Its
time-out period ranges from f
lected by mask option. If time base time-out oc-
curs, the related interrupt request flag (TBF;
bit 5 of INTC1) is set. But if the interrupt is en-
abled, and the stack is not full, a subroutine call
to location 14H occurs. The time base time-out
signal also can be applied to be a clock source of
timer/event counter 1 for getting a longer
timer-out period.
Real time clock - RTC
The real time clock (RTC) is operated in the
same manner as the time base that is used to
supply a regular internal interrupt. Its
time-out period ranges from f
software programming . Writing data to RT2,
RT1 and RT0 (bit2, 1, 0 of RTCC;09H) yields
various time-out periods. If the RTC time-out
occurs, the related interrupt request flag (RTF;
bit 6 of INTC1) is set. But if the interrupt is en-
abled, and the stack is not full, a subroutine call
to location 18H occurs. The real time clock
time-out signal also can be applied to be a clock
source of timer/event counter 0 for getting a
longer time-out period.
S
S
/2
/2
12
8
to f
to f
S
S
/2
/2
15
15
Real time clock
se-
Time base
by
18
Power down operation - HALT
The HALT mode is initialized by the ²HALT²
instruction and results in the following.
·
·
·
RT2
The system oscillator turns off but the WDT
oscillator keeps running (if the WDT oscilla-
tor or the real time clock is selected).
The contents of the on-chip RAM and of the
registers remain unchanged.
The WDT is cleared and start recounting (if
the WDT clock source is from the WDT oscil-
lator or the real time clock oscillator).
0
0
0
0
1
1
1
1
RT1
0
0
1
1
0
0
1
1
RT0
0
1
0
1
0
1
0
1
RTC Clock Divided
Factor
2
2
2
2
2
2
August 18, 1999
2
2
10
11
12
13
14
15
8
9
HT49C50