单片机外文翻译--stc89c52处理芯片

单片机外文翻译--stc89c52处理芯片内容摘要：

external numerical memory, P2 mouth output P2 latches content. In programming and calibration, flash P2 mouth also absorb high eight address byte and some control signal. P3: a P3 mouth on the inside of the eight twoway pullup resistors I/O buffers can drive, p2 output four TTL logic level. For P3 port to write 1, the internal resistance to port, can push as input mouth. When used as input, external and internal foot because of low resistance, will 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。