Considering that the amount of information displayed by the instrument is relatively large, the 192×64 graphic dot matrix liquid crystal block displays information such as frequency, phase difference, and waveform type. Generally speaking, the instrument is divided into hardware and software. The hardware includes 7 units such as single-chip control unit, keyboard input unit and RS232 interface unit. The software includes signal data generation software written in VC++6.0 and MSC- 51 MCU software written in assembly language, two parts, the following two parts are described separately. The hardware design hardware is divided into a single-chip control unit, a dual-channel digital signal generating unit, a keyboard input unit, a storage unit, an A/D conversion unit, a D/A conversion unit, a liquid crystal display unit, an RS232 interface unit, and a signal processing unit, each unit. Connected via a bus. The MCU unit plays a central role in control and operation, ensuring that each unit circuit works in harmony. The specific connection relationship between the units is as shown in the hardware block diagram, as shown in Figure 1. The P0 port of the MCU is used as the data bus of the whole instrument, and the P1, P2 and P3 part interfaces are used as the control bus; P3.0 and P3.1 are used as the serial port connection with the computer interface; P3.2 and P3.3 are respectively used as the keyboard input interrupt And the A/D conversion end interrupts the connection port. The MCU control unit is composed of a single-chip computer with a 8kB flash program memory unit AT89S52 as its core, which plays a role in controlling other parts. Under its control, each part can complete the data exchange and realize the corresponding functions. The dual-channel digital signal generating unit mainly comprises two digital signal generating ICs and corresponding interface circuits. Among them, the digital signal generation IC is AD9833[5]. The integrated chip is a high-performance 28-bit digital control frequency and 12-bit digital control phase, which can produce high-precision sine, triangle and square waves. This instrument uses 12MHz clock crystal oscillator, its numerical control frequency resolution can reach 12M/228 is about 0.04470, and its numerical control phase resolution can reach 360 degrees / 212 is about 0.087890 degrees. It can be seen that the frequency and phase accuracy are both high. The storage unit is mainly composed of a flash memory chip SST39SF04 and its corresponding interface circuit. The flash memory chip has a storage space of 512 kB, mainly due to storing physiological signals and user-defined data, so as to form a physiological signal to be called. The A/D conversion unit is mainly composed of an A/D conversion chip, a corresponding controllable amplification processing circuit, and the like. The 8-channel A/D conversion chip ADC0809 is controlled by the MCU control unit, and the amplified input signal is converted into a digital signal and temporarily stored for display and further processing. In the actual circuit, the A/D conversion and channel address selection are started by the timer of the single-chip microcomputer, and the end signal of the A/D analog-to-digital conversion is used as an interrupt signal to trigger the interrupt of the single-chip microcomputer INT1 (P3.3), with the help of the interrupt service program. Process their data. The D/A conversion unit is mainly composed of a D/A conversion chip, a filtering and amplification processing circuit. Under the control of the single-chip microcomputer, the high-performance 8-bit D/A conversion chip AD558 converts the digital signal into an analog signal, and after processing through filtering and controllable amplification, outputs the desired physiological signal or other signal. The liquid crystal display unit is composed of a liquid crystal display interface circuit and a graphic dot matrix liquid crystal block MCG19264A4-2. Under the control of the single chip microcomputer, the output signal type, frequency and amplitude and related information are displayed, which makes the instrument more intuitive and easier to operate. The RS232 interface unit uses the P3.0 (RXD) and P3.1 (TXD) serial communication ports of the single-chip microcomputer, and the level conversion chip MAX232 constitutes a full-duplex serial port to realize serial communication with the PC computer. Obviously, the signal data defined by the user at any time can be written from the PC computer into the flash memory of the single-chip microcomputer through software to meet the user's needs and generate corresponding signal waveforms. Therefore, the instrument has good openness. The signal processing unit is mainly composed of an analog switch IC, an output power amplifying IC, and a power amplifying IC circuit. The analog switch IC I chose is a four-channel DG201, which selects the desired signal output to power amplification under the action of the microcontroller control unit. The output power amplifier IC has chosen the THS6052 with high output current and has automatic short circuit and thermal protection. (Finish) Sheet metal fabrication processing is formed by laser cutting or stamping process, shear and bending, bending, bending, welding, riveting. The Sheet metal fabrication used are cold-rolled plate (SPCC), hot-rolled plate, galvanized plate (SHCC) (SECC, SGCC), copper (CU) brass, copper, beryllium copper, aluminum (5052), stainless steel. Sheet metal fabrication processing steps: according to the parts drawing (3D) expanded into a plan (2D), laser cutting or die stamping shape, CNC punching each bending part, should pay attention to the direction of the burr of the workpiece. Then the students are welded or riveted (some). Surface treatment after processing: electroplating, passivation, sand blasting (powder), anode treatment. Products are generally made for the connection and the outer cover. Applications in robotics, drone, communications, medical devices, industrial automation equipment. Sheet Metal Fabrication,Oem Sheet Metal Fabrication,Sheet Metal Forming,Sheet Metal Bending Hong Kong RYH CO., LTD , https://www.longfeikitchenware.com
November 19, 2021