33、high-voltage programming mode 5 Pulse ALEPROG once to program a byte in the Flash array or the lock bits The byte-write cycle is self-timedand typically takes no more than 15 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 。

34、Data Polling The AT89C51 features Data Polling to indicate the end of a write cycle During a write cycle anattempted read of the last byte written will result in the complement of the written datum on PO7 Once the write cycle has been completed true data are valid on all outputs and the next cycle m 。

35、ay begin Data Polling may begin any time after a write cycle has been initiated ReadyBusy The progress of byte programming can also be monitored by the RDYBSY output signal P34 is pulled low after ALE goes high during programming to indicate BUSY P34 is pulled high again when programming is done to。

36、indicate READYProgram 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 Ch 。

37、ip Erase The entire Flash array is erased electrically by using the proper combination of control signals and by holding ALEPROG low for 10 ms The code array is written with all 1s The chip erase operation must be executed before the code memory can be re-programmedReading the Signature Bytes The si 。

38、gnature bytes are read by the same procedure as a normal verification of locations 030H 031H and 032H except that P36 and P37 must be pulled to a logic low The values returned are as follows030H 1EH indicates manufactured by Atmel 031H 51H indicates 89C51 032H FFH indicates 12V programming 032H 05H。

39、indicates 5V programmingProgramming InterfaceEvery code byte in the Flash array can be written and the entire array can be erased by using the appropriate combination of control signals The write operation cycle is selftimed and once initiated will automatically time itself to completionAll major pr 。

40、ogramming vendors offer worldwide support for the Atmel microcontroller series Please contact your local programming vendor for the appropriate software revisionFlash Programming and Verification Waveforms - High-voltage Mode VPP 12V Flash Programming and Verification Waveforms - Low-voltage Mode VP 。

41、P 5V Flash Programming and Verification Characteristics TA 0C to 70C VCC 50 10Absolute imum RatingsNOTICE Stresses beyond those listed under Absolute imum Ratings may cause permanent damage to the device This is a stress rating only and functional operation of the device at these or any other condit 。

42、ions beyond those indicated in the operational sections of this specification is not implied Exposure to absolute imum rating conditions for extended periods may affect device reliabilityDC CharacteristicsTA -40C to 85C VCC 50V 20 unless otherwise noted Notes 1 Under steady state non-transient condi 。

43、tions IOL must be externally limited as followsimum IOL per port pin 10 mAimum IOL per 8-bit port Port 0 26 mAPorts 1 2 3 15 mAimum total IOL for all output pins 71 mAIf IOL exceeds the test condition VOL may exceed the related specification Pins are not guaranteed to sink current greater than the l 。

44、isted test conditions2 Minimum VCC for Power-down is 2VAC CharacteristicsUnder operating conditions load capacitance for Port 0 ALEPROG and PSEN 100 pF load capacitance for all other outputs 80 pFExternal Program and Data Memory CharacteristicsExternal Program Memory Read CycleExternal Data Memory R 。

45、ead CycleExternal Data Memory Write CycleExternal Clock Drive WaveformsExternal Clock DriveSerial Port Timing Shift Register Mode Test ConditionsVCC 50 V 20 Load Capacitance 80 pF Shift Register Mode Timing WaveformsAC Testing InputOutput Waveforms 1 Note 1 AC Inputs during testing are driven at VCC 。

46、 - 05V for a logic 1 and 045V for a logic 0 Timing measurements are made at VIH min for a logic 1 and VIL for a logic 0Float Waveforms 1 Note 1 For timing purposes a port pin is no longer floating when a 100mV change from load voltage occurs A port pin begins to float when 100mV change from the load 。

47、ed VOHVOL level occursAT89C51中文原文AT89C51是美国ATMEL公司生产的低电压高性能CMOS8位单片机片内含4k bytes的可反复擦写的只读程序存储器PEROM和128 bytes的随机存取数据存储器RAM器件采用ATMEL公司的高密度非易失性存储技术生产兼容标准MCS-51指令系统片内置通用8位中央处理器CPU和Flash存储单元功能强大AT89C51单片机可为您提供许多高性价比的应用场合可灵活应用于各种控制领域主要性能参数与MCS-51产品指令系统完全兼容4k字节可重擦写Flash闪速存储器1000次擦写周期全静态操作0Hz24MHz三级加密程序存储器1 。

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标题：AT89C51|AT89C51外文翻译毕业设计( 三 )