at89s52單片機(jī)外文翻譯-其他專業(yè)-資料下載頁
2025-01-19 06:20本頁面
【導(dǎo)讀】于各種控制領(lǐng)域。AT89S52提供以下標(biāo)準(zhǔn)功能：4K字節(jié)flish閃速存儲(chǔ)器，128字節(jié)內(nèi)部RAM，工串行通信口，片內(nèi)振蕩器及時(shí)鐘電路。同時(shí)，at89s52可降至0HZ的靜態(tài)邏輯。操作，并支持兩種軟件可選的節(jié)電工作模式。RAM，定時(shí)／計(jì)數(shù)器，串行通信口及中斷系統(tǒng)繼續(xù)工作。掉電方式保存RAM中的。內(nèi)容，但振蕩器停止工作并禁止其它所有部件工作直到下一個(gè)硬件復(fù)位。P0口：P0口是一組8位漏極開路型雙向I/O口，也即地址/數(shù)據(jù)總線復(fù)位口。位）和數(shù)據(jù)總線復(fù)用，在訪問期間激活內(nèi)部上拉電阻。動(dòng)4個(gè)TTL邏輯門電路。對(duì)端口寫“1”，通過內(nèi)部的上拉電。阻把端口拉到高電平，此時(shí)可做熟出口。Flash編程和程序校驗(yàn)期間，P1接受低8位地址。外，該引腳會(huì)被微弱拉高，單片機(jī)執(zhí)行外部程序時(shí)，應(yīng)設(shè)置ALE無效。在此期間，當(dāng)訪問外部數(shù)據(jù)存儲(chǔ)器，這兩次有效的^PSEN信號(hào)。XTAL2分別是該放大器的輸入端和輸出端。續(xù)時(shí)間應(yīng)符合產(chǎn)品技術(shù)要求?；睿纯山K止空閑工作模式。程序會(huì)首先響應(yīng)中斷，進(jìn)入中斷服務(wù)程
【正文】 unction properly. Programming the Flash： The at89s52 is normally shipped with the onchip Flash memory array in the erased state (that is, contents = FFH) and ready to be programmed. The programming interface accepts either a highvoltage (12volt) or a lowvoltage (VCC) program enable signal. The low voltage programming mode provides a convenient way to program the at89s52 inside the user’s system, while the highvoltage programming mode is patible with conventional third party Flash or EPROM programmers. The at89s52 is shipped with either the highvoltage or lowvoltage programming mode enabled. The respective topside marking and device signature codes are listed in the following table. Vpp=12v Vpp=5v Topside mark at89s52 xxxx yyww at89s52 xxxx5 yyww signature (030H)=1EH (031H)=51H (032H)=FFH (030H)=1EH (031H)=51H (032H)=05H The at89s52 code memory array is programmed bytebybyte in either programming mode. To program any nonblank byte in the onchip Flash Programmable and Erasable Read Only Memory, the entire memory must be erased using the Chip Erase Mode. Programming Algorithm: Before programming the at89s52, the address, data and control signals should be set up according to the Flash programming mode table and Figures 3 and 4. To program the at89s52, take the following steps. 1. Input the desired memory location on the address lines. 2. Input the appropriate data byte on the data lines. 3. Activate the correct bination of control signals. 4. Raise EA/VPP to 12V for the highvoltage programming mode. 5. Pulse ALE/PROG once to program a byte in the Flash array or the lock bits. The bytewrite cycle is selftimed and typically takes no more than ms. Repeat steps 1 through 5, changing the address and data for the entire array or until the end of the object file is reached. Data Polling: The at89s52 features Data Polling to indicate the end of a write cycle. During a write cycle, an attempted read of the last byte written will result in the plement of the written datum on . Once the write cycle has been pleted, true data are valid on all outputs, and the next cycle may begin. Data Polling may begin any time after a write cycle has been initiated. Ready/Busy: The progress of byte programming can also be monitored by the RDY/BSY output signal. is pulled low after ALE goes high during programming to indicate BUSY. is pulled high again when programming is done to indicate READY. Program Verify: If lock bits LB1 and LB2 have not been programmed, the programmed code data can be read back via the address and data lines for verification. The lock bits cannot be verified directly. Verification of the lock bits is achieved by observing that their features are enabled. Chip Erase: The entire Flash Programmable and Erasable Read Only Memory array is erased electrically by using the proper bination of control signals and by holding ALE/PROG low for 10 ms. The code array is written with all “1”s. The chip erase operation must be executed before the code memory can be reprogrammed. Reading the Signature Bytes: The signature bytes are read by the same procedure as a normal verification of locations 030H, 031H, and 032H, except that and must be pulled to a logic low. The values returned are as follows. (030H) = 1EH indicates manufactured by Atmel (031H) = 51H indicates 89C51 (032H) = FFH indicates 12V programming (032H) = 05H indicates 5V programming Programming Interface Every code byte in the Flash array can be written and the entire array can be erased by using the appropriate bination of control signals. The write operation cycle is selftimed and once initiated, will automatically time itself to pletion.
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