參數(shù)資料
型號(hào)： HT48CXX
廠商： Holtek Semiconductor Inc.
英文描述： 8-Bit Microcontroller Series
中文描述： 8位微控制器系列
文件頁(yè)數(shù)： 20/59頁(yè)
文件大?。?/td> 2625K
代理商： HT48CXX
The timer/event counter interrupt request flag
(TF), external interrupt request flag (E IF), en-
able timer/event counter bit (E TI), enable exter-
nal interrupt bit (E E I), and enable master
interrupt bit (E MI) constitute an interrupt con-
trol register (INTC) of the HT48C10/HT48C30
which is located at 0BH in the RAM. On the
other hand, the timer/event counter 0/1 inter-
rupt request flag (T0F/T1F), external interrupt
request flag (E IF), enable timer/event counter
0/1 bit (E T0I/E T1I), enable external interrupt
bit (E E I), and enable master interrupt bit (E MI)
make up the interrupt control register (INTC) of
the HT48C50/HT48C70 which is located at 0BH
in the R AM. E MI, E E I, and E T I, of the
HT48C10/HT48C30 or E MI, E E I, E T0I, and
E T1I of the HT48C50/HT48C70 are all used to
control the enable/disable status of interrupts.
These bits prevent the requested interrupt from
being serviced. Once the interrupt request flags
(TF, E IF of the HT48C10/HT48C30 or T0F, T1F,
EIF of the HT48C50/HT48C70) are set, they
will remain in the INTC register until the inter-
rupts are all serviced or cleared by a software
instruction.
It is suggested that a program should not em-
ploy the “CALL subroutine” within the inter-
rupt subroutine, since its operation within the
interrupt subroutine may damage the original
control sequence, and interrupts often occur in
an unpredictable manner or it may need imme-
diate servicing for certain applications. Given
this, if only one stack is left and enabling the
interrupt is not well controlled, the original con-
trol sequence may be ruined as a result of operating
the CALL subroutine in the interrupt subroutine.
Oscillator configuration
There are 2 oscillator circuits available, namely
RC oscillator and crystal oscillator, decided by
mask options. Both are designed for system
clocks. No matter what type of oscillator is cho-
sen, the signal supports the system clock. The
HALT mode stops the system oscillator and ig-
nores any external signals so as to conserve
power.
Of the two oscillator types, if an RC oscillator is
used, an external resistor between OSC1 and
VDD is required and its resistance ranges from
51k
to 1M
. The system clock, divided by 4, is
available on OSC2 (NMOS open drain output),
which can be used to synchronize external logic.
The RC oscillator provides the most cost effec-
tive solution. However, the frequency of the os-
cillation may vary with VDD, temperature and
the chip itself due to process variations. It is,
therefore, not suitable for timing sensitive op-
erations where accurate oscillator frequency is
desired. On the other hand, if the crystal oscil-
lator is used, a crystal across OSC1 and OSC2
is needed to provide the feedback and phase
shift required for the crystal oscillator. No other
external components are required. Instead of a
crystal, the resonator can also be connected be-
tween OSC1 and OSC2 to derive a frequency
reference, but two external capacitors in OSC1
and OSC2 are required.
The WDT oscillator is a free running on-chip RC
oscillator, and no external components are re-
quired. E ven if the system enters the power
down mode, the system clock is stopped but the
WDT oscillator still works with a period of ap-
proximately 78
μ
s. The WDT oscillator can be
disabled by mask option to conserve power.
Watchdog timer – WDT
The clock source of the WDT is implemented by
a dedicated RC oscillator (WDT oscillator) or an
instruction clock (system clock divided by 4),
decided by mask options. The WDT is designed
to prevent a software malfunction or sequence
from jumping to an unknown location with un-
predictable results. The WDT can be disabled
by mask option. If the WDT is disabled, all the
executions related to the WDT may lead to no
operation.
System oscillator
HT48CXX/HT48RXX
20
25th May ’99
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參數(shù)描述
HT48E06 制造商:HOLTEK 制造商全稱:Holtek Semiconductor Inc 功能描述:8-Bit I/O Type MCU (With EEPROM)
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HT48E30 制造商:HOLTEK 制造商全稱:Holtek Semiconductor Inc 功能描述:I/O Type 8-Bit MTP MCU With EEPROM
HT48E50 制造商:HOLTEK 制造商全稱:Holtek Semiconductor Inc 功能描述:I/O Type 8-Bit MTP MCU With EEPROM
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