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參數資料
| 型號： | HT36A0 |
| 廠商： | Holtek Semiconductor Inc. |
| 英文描述： | 8-Bit Music Synthesizer MCU |
| 中文描述： | 8位微控制器音樂合成器 |
| 文件頁數： | 11/23頁 |
| 文件大小： | 257K |
| 代理商： | HT36A0 |
HT36A0
Rev. 1.20
11
June 18, 2003
Oscillator Configuration
The HT36A0 provides two types of oscillator circuit for
the system clock, i.e., RC oscillator and crystal oscilla-
tor. No matter what type of oscillator, the signal divided
by 2 is used for the system clock. The HALT mode stops
the system oscillator and ignores external signal to con-
serve power. If the RC oscillator is used, an external re-
sistor between OSC1 and VSS is required, and the
range of the resistance should be from 30k
The system clock, divided by 4, is available on OSC2
with pull-high resistor, which can be used to synchronize
external logic. The RC oscillator provides the most cost
effective solution. However, the frequency of the oscilla-
tion may vary with VDD, temperature, and the chip itself
due to process variations. It is therefore, not suitable for
timing sensitive operations where accurate oscillator
frequency is desired.
to 680k .
On the other hand, if the crystal oscillator is selected, a
crystalacrossOSC1andOSC2isneededtoprovidethe
feedback and phase shift required for the oscillator, and
no other external components are required. Aresonator
may be connected between OSC1 and OSC2 to replace
the crystal and to get a frequency reference, but two ex-
ternal capacitors in OSC1 and OSC2 are required.
The WDT oscillator is a free running on-chip RC oscilla-
tor, and no external components are required. Even if
the system enters the power down mode, the system
clock is stopped, but the WDToscillator still works with a
period of approximately 78 s. The WDT oscillator can
be disabled by mask option to conserve power.
Watchdog Timer
WDT
The WDT clock source is implemented by a dedicated
RC oscillator (WDT oscillator) or instruction clock (sys-
tem clock of the MCU divided by 4), determined by mask
options. This timer is designed to prevent a software
malfunction or sequence jumping to an unknown loca-
tionwithunpredictableresults.TheWatchdogTimercan
be disabled by mask option. If the Watchdog Timer is
disabled, all the executions related to the WDT result in
no operation.
Once the internal WDT oscillator (RC oscillator with a
period of 78 s normally) is selected, it is first divided by
256 (8-stages) to get the nominal time-out period of ap-
proximately 20ms. This time-out period may vary with
temperature, VDD and process variations. By invoking
the WDT prescaler, longer time-out periods can be real-
ized. Writing data to WS2, WS1, WS0 (bit 2,1,0 of the
WDTS) can give different time-out periods. If WS2,
WS1, WS0 all equal to 1, the division ratio is up to 1:128,
and the maximum time-out period is 2.6 seconds.
If the WDT oscillator is disabled, the WDT clock may still
come from the instruction clock and operate in the same
manner except that in the HALTstate the WDTmay stop
counting and lose its protecting purpose. In this situation
the logic can only be restarted by external logic. The
high nibble and bit 3 of the WDTS are reserved for user
defined flags, and the programmer may use these flags
to indicate some specified status.
WS2
WS1
WS0
Division Ratio
0
0
0
1:1
0
0
1
1:2
0
1
0
1:4
0
1
1
1:8
1
0
0
1:16
1
0
1
1:32
1
1
0
1:64
1
1
1
1:128
If the device operates in a noisy environment, using the
on-chip RC oscillator (WDT OSC) is strongly recom-
mended, since the HALT will stop the system clock.
The WDT overflow under normal operation will initialize
a chip reset and set the status bit TO. Whereas in the
HALT mode, the overflow will initialize a warm reset
only the PC and SP are reset to zero. To clear the WDT
contents (including the WDT prescaler ), 3 methods are
implemented; external reset (a low level to RES), soft-
ware instructions, or a HALT instruction. The software
instructions include CLR WDT and the other set
CLR
7
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6
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6
3
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System oscillator
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Watchdog timer
相關PDF資料 |
PDF描述 |
|---|---|
| HT36A1 | Music Synthesizer 8-Bit MCU |
| HT36A2 | 8-Bit Music Synthesizer MCU |
| HT36A3 | 8-Bit Music Synthesizer MCU |
| HT36A4 | 8-Bit Music Synthesizer MCU |
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相關代理商/技術參數 |
參數描述 |
|---|---|
| HT36A0(48DIP) | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Microcontroller |
| HT36A1 | 制造商:HOLTEK 制造商全稱:Holtek Semiconductor Inc 功能描述:Music Synthesizer 8-Bit MCU |
| HT36A2 | 制造商:HOLTEK 制造商全稱:Holtek Semiconductor Inc 功能描述:8-Bit Music Synthesizer MCU |
| HT36A3 | 制造商:HOLTEK 制造商全稱:Holtek Semiconductor Inc 功能描述:8-Bit Music Synthesizer MCU |
| HT36A4 | 制造商:HOLTEK 制造商全稱:Holtek Semiconductor Inc 功能描述:Music Synthesizer 8-Bit MCU |
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