單片機(jī)外文翻譯--stc89c52處理芯片-在線(xiàn)瀏覽
2025-01-04 04:55本頁(yè)面
【正文】 ll output current IIL . P3 mouth AT89S52 special functions also as the second efficacy , are shown below. In programming and calibration, flash also absorb some P3 mouth control signals. Port pin second efficacy: RXD serial input TXD serial export , INTO the discontinuous 0 INT1 1 the discontinuous time/counter TO 0 T1 1 time/counter, WR external numerical memory write for RD external numerical memory read for In addition, also absorb some used in mp3 mouth FLASH memory programming and calibration of program control signals. RST, reset input: when the vibrator, RST pin appeared two machine cycle above high level will be reset the chip. ALE/PROG when access to external program memory or numerical memory, ALE address latch allow output pulses are used to latch address of low eight bytes. Normally, ALE with clock frequencies are 1/6 output pulse signal with fixed, so it can be used for the purpose or output clocks. Timing Those who want an attention is: whenever access to external numerical memory will skip a ALE pulse. For FLASH memory programming, this pin is used for input programming pulse . PROG If necessary, but through special effect to the zone registers SFR 8EH D0 position, the unit can be banned ALE operations. This position is a bit, MOVX and MOVC instructions will be activated. ALE In addition, the foot will be weak, execute external program MCU hign should be banned, a void. Set ALE PSEN program storage PSEN allowed output is outside of the program memory read, choose munication by external program memory when taking AT89C52 instructions or , each machine cycle PSEN twice, two pulse output is useful, during this period, when access to external numerical memory, will skip PSEN twice. EA/VPP external access permission, to make the CPU only access to external program me
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