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【正文】 In addition, IAP and byteerase allows code memory to be used for nonvolatile data storage. Onchip erase and write timing generation contribute to a userfriendly programming interface. The P89LPC952 flash reliably stores memory contents even after 100,000 erase and program cycles. The cell is designed to optimize the erase and programming mechanisms. The P89LPC952 uses VDD as the supply voltage to perform the Program/Erase algorithms. Features ? Programming and erase over the full operating voltage range. ? Byte erase allows code memory to be used for data storage. ? Read/Programming/Erase using ISP/IAP/ICP. ? Internal fixed boot ROM, containing lowlevel IAP routines available to user code. ? Default loader providing ISP via the serial port, located in upper end of user program memory. ? Boot vector allows userprovided flash loader code to reside anywhere in the flash memory space, providing flexibility to the user. ? Any flash program/erase operation in 2 ms. ? Programming with industrystandard mercial programmers. ? Programmable security for the code in the flash for each sector. ? 100,000 typical erase/program cycles for each byte. ? 10 year minimum data retention. Flash organization The program memory consists of eight 1 kB sectors on the P89LPC952 devices. Each sector can be further divided into 64byte pages. In addition to sector erase, page erase,and byte erase, a 64byte page register is included which allows from 1 to 64 bytes of a given page to be programmed at the same time, substantially reducing overall programming time. Using flash as data storage The flash code memory array of this device supports individual byte erasing and programming. Any byte in the code memory array may be read using the MOVC instruction, provided that the sector containing the byte has not been secured (a MOVC instruction is not allowed to read code memory contents of a secured sector). Thus any byte in a nonsecured sector may be used for nonvolatile data storage. Flash programming and erasing Four different methods of erasing or programming of the flash are available. The flash may be programmed or erased in the e
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