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SN8F22711B 参数 Datasheet PDF下载

SN8F22711B图片预览
型号: SN8F22711B
PDF下载: 下载PDF文件 查看货源
内容描述: 8位微控制器 [8-Bit Micro-Controller]
分类和应用: 微控制器
文件页数/大小: 111 页 / 1291 K
品牌: SONIX [ SONIX TECHNOLOGY COMPANY ]
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SN8F2270B Series  
USB 2.0 Low-Speed 8-Bit Micro-Controller  
4.5 SYSTEM LOW CLOCK  
The system low clock source is the internal low-speed oscillator built in the micro-controller. The low-speed oscillator  
uses RC type oscillator circuit. The frequency is affected by the voltage and temperature of the system. In common  
condition, the frequency of the RC oscillator is about 24KHz.  
The internal low RC supports watchdog clock source and system slow mode controlled by CLKMD.  
)
)
Flosc = Internal low RC oscillator (24KHz).  
Slow mode Fcpu = Flosc / 4  
There are two conditions to stop internal low RC. One is power down mode, and the other is green mode of 24KHz  
mode and watchdog disable. If system is in 24KHz mode and watchdog disable, only 24KHz oscillator actives and  
system is under low power consumption.  
¾
Example: Stop internal low-speed oscillator by power down mode.  
B0BSET  
FCPUM0  
; To stop external high-speed oscillator and internal low-speed  
; oscillator called power down mode (sleep mode).  
’
Note: The internal low-speed clock can’t be turned off individually. It is controlled by CPUM0, CPUM1 (24  
KHz, watchdog disable) bits of OSCM register.  
4.5.1 SYSTEM CLOCK MEASUREMENT  
Under design period, the users can measure system clock speed by software instruction cycle (Fcpu). This way is  
useful in RC mode.  
Example: Fcpu instruction cycle of external oscillator.  
B0BSET  
P0M.0  
; Set P0.0 to be output mode for outputting Fcpu toggle signal.  
@@:  
B0BSET  
B0BCLR  
JMP  
P0.0  
P0.0  
@B  
; Output Fcpu toggle signal in low-speed clock mode.  
; Measure the Fcpu frequency by oscilloscope.  
’
Note: Do not measure the RC frequency directly from XIN; the probe impendence will affect the RC  
frequency.  
SONiX TECHNOLOGY CO., LTD  
Page 46  
Version 1.2