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STC89LE52RC 数据表(PDF) 124 Page - STCmicro Technology Co,.Ltd |
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STC89LE52RC 数据表(HTML) 124 Page - STCmicro Technology Co,.Ltd |
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124 / 165 page  Chapter 9 IAP / EEPROM The ISP in STC89xx series makes it possible to update the user’s application program and non-volatile application data (in IAP-memory) without removing the MCU chip from the actual end product. This useful capability makes a wide range of field-update applications possible. (Note ISP needs the loader program pre-programmed in the ISP-memory.) In general, the user needn’t know how ISP operates because STC has provided the standard ISP tool and embedded ISP code in STC shipped samples. But, to develop a good program for ISP function, the user has to understand the architecture of the embedded flash. The embedded flash consists of 90(max) pages. Each page contains 512 bytes. Dealing with flash, the user must erase it in page unit before writting (programming) data into it. Erasing flash means setting the content of that flash as FFH. Two erase modes are available in this chip. One is mass mode and the other is page mode. The mass mode gets more performance, but it erases the entire flash. The page mode is something performance less, but it is flexible since it erases flash in page unit. Unlike RAM’s real-time operation, to erase flash or to write (program) flash often takes long time so to wait finish. Furthermore,it is a quite complex timing procedure to erase/program flash. Fortunately, the STC89xx carried with convenient mechanism to help the user read/change the flash content. Just filling the target address and data into several SFR, and triggering the built-in ISP automation, the user can easily erase, read, and program the embedded flash and option registers. The In-Application Program feature is designed for user to Read/Write nonvolatile data flash. It may bring great help to store parameters those should be independent of power-up and power-done action. In other words, the user can store data in data flash memory, and after he shutting down the MCU and rebooting the MCU, he can get the original value, which he had stored in. The user can program the data flash according to the same way as ISP program, so he should get deeper un- derstanding related to SFR ISP_DATA, ISP_ADDRL, ISP_ADDRH, ISP_CMD, ISP_TRIG, and ISP_CONTR. 9.1 IAP / ISP Control Register The following special function registers are related to the IAP/ISP operation. All these registers can be accessed by software in the user’s application program. Symbol Description Address Bit Address and Symbol MSB LSB Value after Power-on or Reset ISP_DATA ISP/IAP Flash Data Register E2H 1111 1111B ISP_ADDRH ISP/IAP Flash Address High E3H 0000 0000B ISP_ADDRL ISP/IAP Flash Address Low E4H 0000 0000B ISP_CMD ISP/IAP Flash Command Register E5H ----- MS2 MS1 MS0 xxxx x000B ISP_TRIG ISP/IAP Flash Command Trigger E6H xxxx xxxxB ISP_CONTR ISP/IAP Control Register E7H ISPEN SWBS SWRST -- WT2 WT1 WT0 000x x000B PCON Power Control 87H SMOD SMOD0 - POF GF1 GF0 PD IDL 00x1 0000B 124 |
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