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參數資料
| 型號： | M38517F8SP |
| 元件分類： | 微控制器/微處理器 |
| 英文描述： | 8-BIT, FLASH, 4 MHz, MICROCONTROLLER, PDIP42 |
| 封裝： | 0.600 INCH, 1.78 MM PITCH, PLASTIC, SDIP-42 |
| 文件頁數： | 41/91頁 |
| 文件大小： | 1161K |
| 代理商： | M38517F8SP |
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Rev.1.01
Oct 15, 2003
page 46 of 89
3851 Group (Built-in 24 KB or more ROM)
CLOCK GENERATING CIRCUIT
The 3851 group (built-in 24 KB or more ROM) has two built-in os-
cillation circuits: main clock XIN-XOUT oscillation circuit and sub
clock XCIN-XCOUT oscillation circuit. An oscillation circuit can be
formed by connecting a resonator between XIN and XOUT (XCIN
and XCOUT). Use the circuit constants in accordance with the reso-
nator manufacturer’s recommended values. No external resistor is
needed between XIN and XOUT since a feed-back resistor exists
on-chip. However, an external feed-back resistor is needed be-
tween XCIN and XCOUT.
Immediately after power on, only the XIN oscillation circuit starts
oscillating, and XCIN and XCOUT pins function as I/O ports.
Frequency Control
(1) Middle-speed mode
The internal clock
φ is the frequency of XIN divided by 8. After re-
set is released, this mode is selected.
(2) High-speed mode
The internal clock
φ is half the frequency of XIN.
(3) Low-speed mode
The internal clock
φ is half the frequency of XCIN.
Note
If you switch the mode between middle/high-speed and low-
speed, stabilize both XIN and XCIN oscillations. The sufficient time
is required for the sub-clock to stabilize, especially immediately af-
ter power on and at returning from the stop mode. When switching
the mode between middle/high-speed and low-speed, set the fre-
quency on condition that f(XIN) > 3f(XCIN).
(4) Low power dissipation mode
The low power consumption operation can be realized by stopping
the main clock XIN in low-speed mode. To stop the main clock, set
bit 5 of the CPU mode register to “1”. When the main clock XIN is
restarted (by setting the main clock stop bit to “0”), set sufficient
time for oscillation to stabilize.
The sub-clock XCIN-XCOUT oscillation circuit can not directly input
clocks that are generated externally. Accordingly, make sure to
cause an external resonator to oscillate.
Oscillation Control
(1) Stop mode
If the STP instruction is executed, the internal clock
φ stops at an
“H” level, and XIN and XCIN oscillation stops. When the oscillation
stabilizing time set after STP instruction released bit is “0”, the
prescaler 12 is set to “FF16” and timer 1 is set to “0116”. When the
oscillation stabilizing time set after STP instruction released bit is
“1”, set the sufficient time for oscillation of used oscillator to stabi-
lize since nothing is set to the prescaler 12 and timer 1.
Either XIN or XCIN divided by 16 is input to the prescaler 12 as
count source. Oscillator restarts when an external interrupt is re-
ceived, but the internal clock
φ is not supplied to the CPU (remains
at “H”) until timer 1 underflows. The internal clock
φ is supplied for
the first time, when timer 1 underflows. This ensures time for the
clock oscillation using the ceramic resonators to be stabilized.
Fig. 52 Ceramic resonator circuit
Fig. 53 External clock input circuit
When the oscillator is restarted by reset, apply “L” level to the
RESET pin until the oscillation is stable since a wait time will not
be generated.
(2) Wait mode
If the WIT instruction is executed, the internal clock
φ stops at an
“H” level, but the oscillator does not stop. The internal clock
φ re-
starts at reset or when an interrupt is received. Since the oscillator
does not stop, normal operation can be started immediately after
the clock is restarted.
To ensure that the interrupts will be received to release the STP or
WIT state, their interrupt enable bits must be set to “1” before ex-
ecuting of the STP or WIT instruction.
When releasing the STP state, the prescaler 12 and timer 1 will
start counting the clock XIN divided by 16. Accordingly, set the
timer 1 interrupt enable bit to “0” before executing the STP instruc-
tion.
Note
When using the oscillation stabilizing time set after STP instruction
released bit set to “1”, evaluate time to stabilize oscillation of the
used oscillator and set the value to the timer 1 and prescaler 12.
XCIN
XCOUT
XIN
XOUT
CIN
COUT
CCIN
CCOUT
Rf
Rd
XCIN
XCOUT
XIN
XOUT
CCIN
CCOUT
Rf
Rd
Open
External oscillation
circuit
Vcc
Vss
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相關代理商/技術參數 |
參數描述 |
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| M38517T-ADS | 功能描述:DEV TMP TRGT BRD FOR M38517RSS & RoHS:否 類別:編程器，開發(fā)系統(tǒng) >> 配件 系列:- 標準包裝:1 系列:- 附件類型:適配器板 適用于相關產品:RCB230，RCB231，RCB212 配用:26790D-ND - RCB BREAKOUT BOARD RS232 CABLE |
| M38517T-PAC | 功能描述:DEV SIMPLE TOOL EMULATOR FOR M38 RoHS:否 類別:編程器，開發(fā)系統(tǒng) >> 內電路編程器、仿真器以及調試器 系列:- 產品變化通告:Development Systems Discontinuation 19/Jul/2010 標準包裝:1 系列:* 類型:* 適用于相關產品:* 所含物品:* |
| M3852 BK001 | 制造商:Alpha Wire 功能描述:CBL 8COND 14AWG BLK 1000' |
| M3852 BK002 | 制造商:Alpha Wire 功能描述:CBL 8COND 14AWG BLK 500' |
| M3852 BK005 | 制造商:Alpha Wire 功能描述:CBL 8COND 14AWG BLK 100' |
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