參數資料
型號: HT48R30A
廠商: Holtek Semiconductor Inc.
元件分類: 數學處理器
英文描述: 8-BIT MICROCONTROLLER
中文描述: 8位微控制器
文件頁數: 12/43頁
文件大?。?/td> 710K
代理商: HT48R30A
HT48R30A-1
Rev. 1.10
12
July 2, 2001
used to control the enabling/disabling of inter-
rupts. These bits prevent the requested inter-
rupt from being serviced. Once the interrupt
request flags (TF, EIF) are set, they will remain
in the INTC register until the interrupts are
serviced or cleared by a software instruction.
It is recommended that a program does not
use the "CALL subroutine" within the inter-
rupt subroutine. Interrupts often occur in an
unpredictable manner or need to be serviced
immediately in some applications. If only one
stack is left and enabling the interrupt is not
well controlled,theoriginalcontrolsequencewill
be damaged once the "CALL" operates in the in-
terrupt subroutine.
Oscillator configuration
There are 3 oscillator circuits in the
microcontroller.
All of them are designed for system clocks,
namely the external RC oscillator, the external
Crystal oscillator and the internal RC
oscillator, which are determined by ROM code
option. No matter what oscillator type is se-
lected, the signal provides the system clock.
The HALT mode stops the system oscillator
and ignores an external signal to conserve
power.
If an RC oscillator is used, an external resistor
between OSC1 and VDD is required and the
resistance must range from 51k
system clock, divided by 4, is available on
OSC2, which can be used to synchronize exter-
nal logic. The RC oscillator provides the most
cost effective solution. However, the frequency
of oscillation may vary with VDD, tempera-
tures and the chip itself due to process varia-
tions. It is, therefore, not suitable for timing
sensitive operations where an accurate oscilla-
tor frequency is desired.
to 1M . The
If the Crystal oscillator is used, a crystal across
OSC1 and OSC2 is needed to provide the feed-
back and phase shift required for the oscillator.
No other external components are required. In
stead of a crystal, a resonator can also be con-
nected between OSC1 and OSC2 to get a fre-
quency reference, but two external capacitors
in OSC1 and OSC2 are required. If the internal
RC oscillator is used, the OSC1 and OSC2 can
be selected as gene ral I/O lines or an 32768Hz
crystal oscillator (RTC OSC). Also, the frequen-
cies of the internal RC oscillator can be
3.2MHz, 1.6MHz, 800kHz and 400kHz (de-
pends on the options).
The oscillator is a free running on-chip RC oscil-
lator, and no external components are required.
Even if the system enters the power down mode,
thesystemclockisstopped,buttheoscillatorstill
works within a period of 72 s. The WDT oscilla-
tor can be disabled by ROM code option to con-
serve power.
Watchdog Timer
WDT
The WDT clock source is implemented by a ded-
* ! ' = &
3 ; @ # ! ' !
-
'
0 ; @ # ! ' !
3 ; ! ; '
-
' # ; !
- . -
+
" ! #
!
-
'
Watchdog Timer
* !' #
8 + ' 5 0 4 3 > 9
' #
' " '
#
&
& 0 " 7
System oscillator
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