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Industry Information
What controls does the ultrasonic flowmeter use?
2012-3-9 12:37:52

采用AVR高档单片机控制单片机是一种在一块芯片上集成了CPU.RAM/ ROM、定时器/计数器和I/O接口等单元的微控制芯片, 具有速度快,功能强、效率高、体积小,性能可靠、抗干扰能力强等优点,在各种控制系统中应用广泛。 1. The ultrasonic flowmeter adopts AVR high-end single-chip microcomputer control. The single-chip microcomputer is a micro-control chip that integrates CPU, RAM / ROM, timer / counter and I / O interface on a chip. It has fast speed, strong function and efficiency. The advantages of high size, small size, reliable performance and strong anti-interference ability are widely used in various control systems. The CPU of the single-chip microcomputer has undergone a development process from 4, 8, 16, 32 to 64 bits. In the ultrasonic generator, the single-chip microcomputer is mainly used for data acquisition and calculation processing, voltage and current adjustment, PWM signal generation, system status monitoring, and fault self-diagnosis. It generally operates as the main control chip of the entire circuit and completes a variety of comprehensive functions. Cooperate with D / A converter and MOSFET power module to realize pulse width modulation. In addition, the single-chip microcomputer also has over current and over heat. Interrupt protection and monitoring functions for undervoltage conditions. The single-chip microcomputer control overcomes the inherent defects of the analog circuit. Through the digital control method, it obtains high-precision and high-stability control characteristics, and can realize flexible and diverse control functions.

采用DSP控制数字信号处理器{DSP}是近年来迅速崛起的新一代可编程处理器。 2. The ultrasonic flowmeter adopts DSP to control the digital signal processor {DSP}, which is a new-generation programmable processor that has risen rapidly in recent years. Its internal integrated baud rate ultrasonic generator and FiFO buffer provide high-speed synchronous serial port and standard asynchronous serial port. Some chips also integrate sample / hold and A / D conversion circuits, and provide PWM signal output. Compared with single-chip microcomputers, DSPs have faster CPUs. Higher integration and larger capacity memory. DSP is a reduced instruction system computer (Risc). Most instructions can be completed in one cycle and multiple instructions can be completed in one instruction cycle through parallel processing technology. At the same time, the DSP uses an improved Harvard structure with independent program and data spaces, allowing programs and data to be stored simultaneously. Built-in high-speed hardware multiplier adds multi-stage pipeline. Make it have high-speed data computing ability. The single-chip microcomputer is a complex instruction system computer (CiSC). Most of the instructions can be completed in 2-3 instruction cycles. The single-chip microcomputer uses a Neumann structure, and programs and data are stored in the same space, and only instructions or data can be accessed at the same time. The ALU of a single-chip microcomputer can only perform addition, and multiplication needs to be implemented by software, so it takes more instruction cycles and is slower. Compared with 16-bit microcontrollers. DSP executes a single instruction 8-10 times faster, and a multiplication operation 16-16 times faster. In the sonotrode. DSP can complete all functions except power conversion, such as main circuit control, system real-time monitoring and protection. Although DSP has many advantages, it also has some limitations, such as the selection of sampling frequency, PWM signal frequency and its accuracy, Sampling delay, calculation time and accuracy. These factors will more or less affect the control performance of the ultrasonic flowmeter circuit.

采用FPGA控制现场可编程门阵列(FPGA)属于可重构器件,其内部逻辑功能可以根据需要任意设定,具有集成度高、处理速度快。 3. The ultrasonic flowmeter uses FPGA to control the field programmable gate array (FPGA), which is a reconfigurable device. Its internal logic function can be arbitrarily set according to needs, with high integration and fast processing speed. High efficiency. Its structure is mainly divided into three parts: programmable logic blocks, programmable I / O modules, and programmable internal wiring. Due to the very high degree of integration of FPGAs, an FPGA can range from a few thousand equivalent gates to as many as tens of thousands or hundreds of thousands of equivalent gates. Therefore, an FPGA can implement very complex logic. It can replace multiple integrated circuits and discrete components. It uses the hardware description language (VHDL) to design the system. It uses three levels of hardware description (behavior description, PJL description, and gate-level description) and a top-down (starting from system function description) design style. The three levels of description are mixed and simulated, so that digital circuit design can be conveniently performed, which has considerable advantages in reliability, size and cost. In comparison, DSP is suitable for occasions with low sampling rate and high software complexity; and When the system sampling rate is high (MHz level), the data rate is high (more than 20MB / s), the condition operation is small, and the task is relatively fixed, FPGA has more advantages.