微型计算机控系统(单片机控制系统) 毕业论文外文翻译
英语翻译
Microcontroller reset is to make the CPU and other system features are in a defined initial state, and from this state to work, reset PC = 0000H, the microcontroller from the first - a unit to take command. Whether it is connected to the microcontroller when the power is just the beginning, or after power failure or failure to be reset. MCU reset conditions are: the RST pin must be coupled with continued two machine cycles (ie 24 oscillations) is high. Clock frequency in this article 12MHz, each machine cycle is 1μs, then the only 2μs time high above, appears in the RST pin high after the implementation of the second machine cycle reset.
Reset circuit constituted by the capacitor series resistance, combined with the map, "the capacitor voltage can not be mutated"in nature, can know when the system is a power, RST will be a foot high, and that the duration of this high by the circuit The RC values to decide. Appropriate combination of RC values can ensure a reliable reset. The circuit in addition to a power-on reset functions, to reset, just press the RESET button, then power through resistance, voltage, reset in the RESET high end.
Clock circuit main task is to provide a working frequency. Internal microcontroller used to form a high-gain inverting amplifier oscillator, the amplifier input and output are XTAL1 and XTAL2, XTAL1 and XTAL2 on the external clock source can constitute a clock circuit. Both internal and external clock generation mode. This design uses the internal clock generation means. Circuit connection shown in Figure 3.2, both ends of the jumper XTAL1 and XTAL2 crystal resonator (oscillator frequency 12MHZ), and internal self-excited oscillator inverter constituted. The issue of pulse timing control directly into the on-chip components. In addition, the capacitance of the frequency tuning role, as an external crystal oscillator, capacitor selection 20pF, practical application, and capacitor resonator near as possible to install in
