The peripheral circuit of the wheel speed sensor hardware structure with 80C31 single chip as the core has signal processing circuit, bus control and bus interface.
Filter mesh refers to small aperture metal mesh or other materials with smaller apertures for a variety of different filtration, dust removal and separation requirements. They are widely used in shower panel, sanitary pipe systems, purifiers, electronic components, to remove contaminants or in applications, such as coffee machine, soya milk machine, to extract a filter cake. Because the metal mesh filters are one of the most durable filter media available, the material is mainly made of copper, iron, steel, nickel, stainless steel, alloy. It is acid resistant, alkali resistant, temperature resistant and wear resistant.
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Flow Rate
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After the wheel speed sensor generates a signal, it is filtered, shaped, and optically isolated, and sent to the /INT0 input pin of the 80C31. T1 is used as a timer to periodically measure the pulse signal. SJA1000, 82C250 form the control and interface circuit with CAN bus. In the design process of the wheel speed sensor, full consideration is given to its anti-jamming and stability. The input/output terminals of the MCU are optically isolated, and the watchdog timer (MAX813) is used for time-out reset to ensure reliable operation of the system.
Signal processing circuit design According to the wheel speed sensor signal characteristics, the processing circuit consists of a limiting circuit, a filtering circuit and a comparison shaping circuit, as shown in Figure 4. 
The limiting circuit limits the amplitude of the positive half cycle of the wheel speed sensor output signal Vi to 5V or less, and the output of the negative half cycle to -0.6V. The filter circuit is designed as an active low-pass filter with feedback, and its cutoff frequency is 2075Hz ( According to the maximum speed of 200km/h, the frequency corresponding to the sensor output signal), select Q=0.707. Compare the shaping circuit to set a certain comparison voltage, and output the square wave signal compared with the filter output signal. The amplitude of the LM311N output square wave is 10V. After R5 and R6 are divided, the square wave signal with the amplitude of 5V is sent to the optical isolator.
One of the most significant advantages metal mesh has over most filter media used today is its ability to deliver an adequate flow rate. This is achievable as the wire diameter and mesh opening can be customized to perfectly match the contaminants you are filtering out, providing you with an enhanced level of filtration surface area.
Durability
300 series stainless steel is predominantly used. This helps create a filter that can withstand a wide range of impurities, pressure variations, and extreme temperatures without hindering the filter's accuracy. In addition, stainless steel is a very pliable material, allowing the filter to be formed to fit your filter system and hold its shape after several uses.
Accuracy
The weaving process used to construct mesh filters is heavily monitored from start to finish. As a result, the pore openings of the filter are exact and uniform throughout the filter. These precise pore opinings ensure that the end product, whether a filtered substance or a filter cake, is consistent and complies with industry standards.
Clean ability
As metal mesh features accurate pore openings, blinding and plugging are significantly reduced. This, combined with the enhanced flow rate, means system operators can clean the metal mesh easily. These two properties allow the mesh filter to be backflushed and purged of any unwanted debris with minimal pressure.