Explaining the Core of Single Chip Microcomputer in PCB Design

The function of crystal oscillator circuit is to provide qualified clock signal flow. If you have learned digital circuit, you will know that the single chip microcomputer icircuit s composed of countless PCB circuits, and the gate circuit needs a signal as a trigger when it is working. When one pulse comes, the gate circuit will execute once, and when several pulses come, the gate circuit will execute several times. Therefore, under the same PCB circuit condition, the higher the pulse frequency, the higher the performance of the microcontroller.

Single chip microcomputer (English: Single Chip Microcomputer), also known as microcontroller, is a microcomputer that integrates central processor, memory,

 timer/counter, various input/output interfaces, etc. on an integrated circuit chip. Compared with the general-purpose microprocessor used in personal computers with PCB, it emphasizes self supply (no external hardware) and cost saving. Its biggest advantage is that it is small in size and can be placed inside the instrument, but it has small storage capacity, simple input/output interface and low function. Because of its rapid development, the old definition of SCM can not meet the requirements, so it is called a broader range of microcontroller in many applications; From the 1980s, the 4-bit and 8-bit MCU was developed to the current 32-bit 300M MCU.

Crystal oscillator circuit is used to control the beat of program operation. High speed means high frequency and fast beat; Low speed, otherwise.

The function of single chip crystal oscillator is to provide the basic clock signal for the system. Generally, one system shares one crystal oscillator, which is convenient for local synchronization. In some communication systems, different crystal oscillators are used for the fundamental frequency and radio frequency, and the synchronization is maintained through electronic frequency adjustment.

The crystal oscillator is usually used in combination with the phase-locked loop circuit to provide the clock frequency required by the system. If different subsystems need different frequency clock signals, they can be provided by different phase-locked loops connected to the same crystal oscillator.

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Under normal working conditions, the absolute accuracy of ordinary crystal frequency can reach 50 parts per million. Advanced precision is higher. Some crystal oscillators can also adjust the frequency within a certain range by the applied voltage, which is called voltage controlled oscillator (VCO). Crystal oscillator uses a crystal that can convert electrical energy and mechanical energy into each other to work in a resonant state to provide stable and accurate single frequency oscillation.

There are crystal oscillators in the single chip microcomputer system. The crystal oscillator plays a very important role in the single chip microcomputer system. The whole process is called crystal oscillator. It separates the internal circuit of the single chip microcomputer to generate the clock frequency required by the single chip microcomputer. The higher the clock frequency provided by the single chip microcomputer crystal oscillator, the faster the single chip microcomputer will run. The execution of all instructions received by the single chip microcomputer is based on the clock frequency provided by the single chip microcomputer crystal oscillator.

Under normal working conditions, the absolute accuracy of ordinary crystal frequency can reach 50 parts per million. Advanced precision is higher. Some crystal oscillators can also adjust the frequency within a certain range by the applied voltage, which is called voltage controlled oscillator (VCO). Crystal oscillator uses a crystal that can convert electrical energy and mechanical energy into each other to work in a resonant state to provide stable and accurate single frequency oscillation.

The function of the PCB monolithic integrated circuit crystal oscillator is to provide the fundamental clock signal for the system. Generally, one system shares one crystal oscillator, which is convenient for local synchronization. In some communication systems, different crystal oscillators are used for the fundamental frequency and radio frequency, and the synchronization is maintained through electronic frequency adjustment.

The crystal oscillator is usually used in combination with the phase-locked loop circuit to provide the clock frequency required by the PCB system. If different subsystems need different frequency clock signals, they can be provided by different phase-locked loops connected to the same crystal oscillator.

STC89C51 uses the 11.0592MHz crystal oscillator as the oscillation source. Since the microcontroller has an oscillation circuit inside, it only needs to connect one crystal oscillator and two capacitors outside. The capacitance is generally between 15pF and 50pF.