微控制器外文翻譯-其他專業(yè)(編輯修改稿)
2025-02-24 11:30 本頁面
【文章內(nèi)容簡介】 n SFR AUXR (address 8EH) can be used to disable this feature. In the default state of bit DISRTO, the RESET HIGH out feature is enabled. ALE/PROG Address Latch Enable (ALE) is an output pulse for latching the low byte of the address during accesses to external memory. This pin is also the program pulse input (PROG) during Flash programming. In normal operation, ALE is emitted at a constant rate of 1/6 the oscillator frequency and may be used for external timing or clocking purposes. Note, however, that one ALE pulse is skipped during each access to external data memory. If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the bit set, ALE is active only during a MOVX or MOVC instruction. Otherwise, the pin is weakly pulled high. Setting the ALEdisable bit has no effect if the microcontroller is in external execution mode. PSEN Program Store Enable (PSEN) is the read strobe to external program memory. When the AT89S52 is executing code from external program memory, PSEN is activated twice each machine cycle, except that two PSEN activations are skipped during each access to external data memory. EA/VPP External Access Enable. EA must be strapped to GND in order to enable the device to fetch code from external program memory locations starting at 0000H up to FFFFH. Note, however, that if lock bit 1 is programmed, EA will be internally latched on reset. EA should be strapped to V for internal program pin also receives the 12volt programming enable voltage (V ) during Flash programming. XTAL1： Input to the inverting oscillator amplifier and input to the internal clock operating circuit. XTAL2： Output from the inverting oscillator amplifier. 3. Timer 0 and Timer1 Timer 0 and Timer 1 in the AT89S52 operate the same way as Timer 0 and Timer 1 in the AT89C51 and AT89C52. For further information on the timers’ operation, please click on the document link below: 4. Timer 2 Timer 2 is a 16bit Timer/Counter that can operate as either a timer or an event counter. The type of operation is selected by bit C/T2 in the SFR T2CON (shown in Table 52). Timer 2 has three 4 operating modes: capture, autoreload (up or down counting), and baud rate generator. The modes are selected by bits in T2CON, as shown in Table 101. Timer 2 consists of two 8bit registers, TH2 and TL2. In the Timer function, the TL2 register is incremented every machine cycle. Since a machine cycle consists of 12 oscillator periods,
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