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PIC18F4431-I/PT 参数 Datasheet PDF下载

PIC18F4431-I/PT图片预览
型号: PIC18F4431-I/PT
PDF下载: 下载PDF文件 查看货源
内容描述: 28 /40/ 44引脚增强型闪存微控制器采用纳瓦技术,高性能PWM和A / D [28/40/44-Pin Enhanced Flash Microcontrollers with nanoWatt Technology, High-Performance PWM and A/D]
分类和应用: 闪存微控制器
文件页数/大小: 392 页 / 3127 K
品牌: MICROCHIP [ MICROCHIP ]
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PIC18F2331/2431/4331/4431  
The long write is necessary for programming the  
8.5  
Writing to Flash Program Memory  
internal Flash. Instruction execution is halted while in a  
long write cycle. The long write will be terminated by  
the internal programming timer.  
The programming block size is 4 words or 8 bytes.  
Word or byte programming is not supported.  
Table writes are used internally to load the holding  
registers needed to program the Flash memory. There  
are 8 holding registers used by the table writes for  
programming.  
The EEPROM on-chip timer controls the write time.  
The write/erase voltages are generated by an on-chip  
charge pump, rated to operate over the voltage range  
of the device.  
Since the Table Latch (TABLAT) is only a single byte,  
the TBLWT instruction has to be executed 8 times for  
each programming operation. All of the table write  
operations will essentially be short writes, because only  
the holding registers are written. At the end of updating  
8 registers, the EECON1 register must be written to, to  
start the programming operation with a long write.  
Note:  
The default value of the holding registers  
on device Resets and after write operations  
is FFh. A write of FFh to a holding register  
does not modify that byte. This means that  
individual bytes of program memory may  
be modified, provided that the modification  
does not attempt to change any bit from a  
0’ to a ‘1’. When modifying individual  
bytes, it is not necessary to load all 64 hold-  
ing registers before executing a write  
operation.  
FIGURE 8-5:  
TABLE WRITES TO FLASH PROGRAM MEMORY  
TABLAT  
Write Register  
8
8
8
8
TBLPTR = xxxxx0  
TBLPTR = xxxxx2  
Holding Register Holding Register  
TBLPTR = xxxxx7  
TBLPTR = xxxxx1  
Holding Register  
Holding Register  
Program Memory  
2010 Microchip Technology Inc.  
DS39616D-page 91  
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