HT49C30-1 Ver la hoja de datos (PDF) - Holtek Semiconductor
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HT49C30-1 Datasheet PDF : 43 Pages
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HT49R30A-1/HT49C30-1/HT49C30L
external reset (a low level to RES), software instruction,
and a ²HALT² instruction. There are two types of soft-
ware instructions; ²CLR WDT² and the other set - ²CLR
WDT1² and ²CLR WDT2². Of these two types of instruc-
tion, only one type of instruction can be active at a time
depending on the options - ²CLR WDT² times selection
option . If the ²CLR WDT² is selected (i.e., CLR WDT
times equal one), any execution of the ²CLR WDT² in-
struction clears the WDT. In the case that ²CLR WDT1²
and ²CLR WDT2² are chosen (i.e., CLR WDT times
equal two), these two instructions have to be executed
to clear the WDT; otherwise, the WDT may reset the
chip due to time-out.
Multi-function timer
The device provides a multi-function timer for the WDT,
time base and RTC but with different time-out periods.
The multi-function timer consists of a 8-stage divider
and an 7-bit prescaler, with the clock source coming
from the WDT OSC or RTC OSC or the instruction clock
(i.e.., system clock divided by 4). The multi-function
timer also provides a selectable frequency signal
(ranges from fS/22 to fS/28) for LCD driver circuits, and a
selectable frequency signal (ranges from fS/22 to fS/29)
for the buzzer output by options. It is recommended to
select a near 4kHz signal to LCD driver circuits for
proper display.
Time base
The time base offers a periodic time-out period to gener-
ate a regular internal interrupt. Its time-out period
ranges from /212 to fS/215 selected by options. If time
base time-out occurs, the related interrupt request flag
(TBF; bit 4 of INTC1) is set. But if the interrupt is en-
abled, and the stack is not full, a subroutine call to loca-
tion 10H occurs.
Real time clock - RTC
The real time clock (RTC) is operated in the same man-
ner as the time base that is used to supply a regular in-
ternal interrupt. Its time-out period ranges from fS/28 to
fS/215 by 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 5 of INTC1) is set. But if
the interrupt is enabled, and the stack is not full, a sub-
routine call to location 14H occurs. The real time clock
time-out signal also can be applied to be a clock source
of timer/event counter for getting a longer time-out pe-
riod.
S y s te m C lo c k /4
R TC
O S C 32768H z
W
O
DT
SC
12kH
z
O p tio n fS
S e le c t
fs
D iv id e r
D iv id e r
CK T
R
CK T
R
W D T C le a r
Watchdog Timer
D iv id e r
P r e s c a le r
T im e - o u t R e s e t fS /2 1 5 ~ fS /2 1 6
Rev. 1.10
O p tio n
O p tio n
L C D D riv e r (fS /2 2~ fS /2 8)
B u z z e r (fS /2 2~ fS /2 9)
T im e B a s e In te rru p t
fS /2 12~ fS /2 15
Time base
fS
D iv id e r
P r e s c a le r
R T2
8 to 1
R T1
R T0
M ux.
Real time clock
fS /2 8~ fS /2 15
R T C In te rru p t
14
September 25, 2002
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