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SN8F2251B 参数 Datasheet PDF下载

SN8F2251B图片预览
型号: SN8F2251B
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: 133 页 / 1554 K
品牌: SONIX [ SONIX TECHNOLOGY COMPANY ]
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SN8F2250B Series  
USB 2.0 Full-Speed 8-Bit Micro-Controller  
3
RESET  
3.1 OVERVIEW  
The system would be reset in three conditions as following.  
z
z
z
z
Power on reset  
Watchdog reset  
Brown out reset  
External reset (only supports external reset pin enable situation)  
When any reset condition occurs, all system registers keep initial status, program stops and program counter is cleared.  
After reset status released, the system boots up and program starts to execute from ORG 0. The NT0, NPD flags  
indicate system reset status. The system can depend on NT0, NPD status and go to different paths by program.  
086H  
PFLAG  
Read/Write  
After reset  
Bit 7  
NT0  
R/W  
-
Bit 6  
NPD  
R/W  
-
Bit 5  
Bit 4  
Bit 3  
Bit 2  
C
R/W  
0
Bit 1  
DC  
R/W  
0
Bit 0  
Z
R/W  
0
-
-
-
-
-
-
-
-
-
Bit [7:6] NT0, NPD: Reset status flag.  
NT0  
0
0
1
1
NPD  
Condition  
Watchdog reset  
Reserved  
Power on reset and LVD reset. Power voltage is lower than LVD detecting level.  
External reset External reset pin detect low level status.  
Description  
Watchdog timer overflow.  
-
0
1
0
1
Finishing any reset sequence needs some time. The system provides complete procedures to make the power on reset  
successful. For different oscillator types, the reset time is different. That causes the VDD rise rate and start-up time of  
different oscillator is not fixed. RC type oscillator’s start-up time is very short, but the crystal type is longer. Under client  
terminal application, users have to take care the power on reset time for the master terminal requirement. The reset  
timing diagram is as following.  
LVD Detect Level  
VDD  
VSS  
Power  
External Reset  
Watchdog Reset  
System Status  
VDD  
VSS  
External Reset  
High Detect  
External Reset  
Low Detect  
Watchdog  
Overflow  
Watchdog Normal Run  
Watchdog Stop  
System Normal Run  
System Stop  
Power On  
Delay Time  
External  
Reset Delay  
Time  
Watchdog  
Reset Delay  
Time  
SONiX TECHNOLOGY CO., LTD  
Page 38  
Version 1.1