Application of Digital Control Technology to Ultrasonic Generator

1. The ultrasonic generator is controlled by AVR high-grade single chip microcomputer


Single chip microcomputer has the advantages of fast speed, strong function, high efficiency, small size, reliable performance, strong anti-interference ability, etc., and is widely used in various control systems. The CPU of single chip microcomputer has gone through the development process from 4, 8,16, 32 to 64 bits. In the ultrasonic transducer used in a medical, single chip microcomputer is mainly used for data acquisition and operation processing, voltage and current regulation, PWM signal generation, system status monitoring and fault self-diagnosis, etc. It is generally operated as the main control chip of the whole circuit and completes various comprehensive functions. Cooperate with converter and power module to realize pulse width modulation.


2. The ultrasonic generator is controlled by DSP


Digital signal processors are a new generation of programmable processors that have risen rapidly in recent years. It integrates baud rate ultrasonic generator and buffer, provides high-speed synchronous serial port and standard asynchronous serial port, and some on-chip also integrates sample/hold and A/D conversion circuits, and provides PWM signal output. Compared with single chip microcomputer, DSP has a faster CPU. Higher integration and larger capacity of memory. DSP is a thin instruction system computer, most instructions can be completed in one cycle and can be completed in one instruction cycle through parallel processing technology. At the same time, DSP adopts an improved Harvard structure with independent program and data space, allowing simultaneous storage of program and data. Built-in high-speed hardware multiplier, adding multi-stage pipeline. It has high-speed data computing power. The microcontroller is a complex instruction system computer, most instructions need 2-3 instruction cycles to complete. Single chip microcomputer adopts Neumann structure, programs and data are stored in the same space, and instructions or data can only be accessed separately at the same time. The ALU of the microcontroller can only do addition, and multiplication needs to be implemented by software, so it needs to take up more instruction cycles and the speed is relatively slow.


3. The ultrasonic generator is controlled by FPGA


The field programmable gate array is used in reconfigurable devices, and its internal logic functions can be set arbitrarily as needed. It has the advantages of high integration, fast processing speed and high efficiency. Its structure is mainly divided into three parts: programmable logic block, programmable I/O module and programmable internal connection. Because the integration level of FPGA is very large, a piece of FPGA can have as few as thousands of equivalent gates and as many as tens of thousands or hundreds of thousands of equivalent gates, so a piece of FPGA can realize very complex logic. Replace a circuit composed of multiple integrated circuits and discrete components. With the help of hardware description language to design the system, using three levels of hardware description and top-down design style, the description of the three levels of mixed simulation, so that it can be convenient for digital circuit design, in reliability, volume, cost has considerable advantages. Comparatively speaking, DSP is suitable for occasions with low sampling rate and high software complexity. However, FPGA control of ultrasonic generator is more advantageous when the system has high sampling rate, high data rate, few conditional operations and relatively fixed tasks.

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