Design Of Drill Break And Diameter Detection System Based On FPGA

With the rapid development of electronics industry, the design of modern electronic circuit develops toward the integration and miniaturization direction. Particularly in the manufacturing process of printed circuit board (PCB), the dimension of appearance is not only smaller and smaller, but also the size of hole is getting smaller and smaller, and the numbers of hole is more and more on board. Thus the size and quality of PCB drill is demanding increasingly. The quality equipment of drill testing is backward relatively at home, and the cost of the equipment is expensive aboard, so this paper designs and develops a quality equipment of drill testing with excellent performance and low-cost, based on researching the external structure and working principle of digital control drilling machine of PCB.This paper starts researching around the drill quality detection, for the quality issue of drill break and drill diameter, develops and designs a low-cost drill break and diameter detection system based on FPGA. By anglicizing the basic theory and basic methods of photoelectric sensor technology with signal processing algorithms, constructs a system test program which contains drill break detection module and drill diameter detection module, and combining with the characteristics of FPGA processor, deals the signal detection algorithms and image processing algorithms with hardware, designs and produces a drill break detection and diameter drill system based on FPGA.In the drill break detection module, this paper first designed a photoelectric sensor based on the induction principle of photovoltaic cell, which mainly includes the designing of filter circuit, amplifier, shaping circuit and the differential transmission circuit. Especially in the amplification circuit, it designed a selective amplifier only for the detecting signal, which can effectively shield the white noise signal; then constructed a hardware architecture based on FPGA; finally developed drill break detection procedures based on VHDL.In the drill diameter detection module, this paper analyzed and studied the working principle and using way of CMOS digital image sensor; designed and produced a circuit combining the CMOS digital image sensor with FPGA; analysis and studied the drill image pre-processing and processing algorithms of diameter and partial corner detection, during the algorithm processing, by dealing with the pure hardware language to realize all algorithms, that was meaning all algorithms implemented by the hardware, thus can accelerate the speed of the whole detection module greatly; designed and produced a multi-machine communications network based on the RS-485 serial communication principle, thus PC can communicate with multi-block FPGA chip simultaneously; developed an application of the drill diameter and angle data processing based on VC + + development platform.The system runs on the digital control drilling machine of PCB, and the test results show that the overall designing of the system is feasible, and has reached the desired goal in the detection speed and detection accuracy, especially production cost is far lower than similar foreign detection equipment, but also meets the real-time and accuracy requirements for the digital control drilling machine of PCB. Presently the system runs well in the actual digital control drilling machine of PCB.