The Testing System Of Laser Rangefinder Board Based On STM32 And CPLD

In the case of mass production of laser rangefinder board, manual quality testing and functional verification are usually time-consuming and inefficient. Therefore, the Automatic Test Equipment (ATE) is required. The primary points of the ATE for laser rangefinder board are signal sampling of key locations and the information acquisition of ranging performance. However, it appears to be difficult to obtain the information, because laser ranging is generally carried out outdoors, which asks for large space with targets in different distance.To solve the problem, first of all, the subject of the research background and research status are summarized, the principle of laser ranging and laser ranging board test are analyzed theoretically. Secondly a new type of signal simulator called simulated laser distance source is designed, which can simulate the flight time of laser and the electrical pulse amplitude produced by laser detecting APD. On this basis, the overall architecture of the testing system is completed. Again, the laser ranging board testing system is designed and implemented based on the STM32 and CPLD, completing A/D, D/A module, serial communication module, frequency measurement module and so on. At the same time, PC software is designed and implemented based on the MFC. This system was tested, and the test results are analyzed and summarized.There are two major contributions in the paper. Firstly, a new strategy is used in simulated laser distance source, namely, CPLD based timing control unit is used to control the high-speed analog switch’s on-off state, which can simulate the flight time of laser precisely. D/A module is used to control the amplitude of the laser echo-wave electrical pulse. There comes a type of laser echo-wave electrical pulse with high-precision time difference and adjustable amplitude. By those, laser distance source can simulate targets in different distance well and laser ranging can be simulated indoors. Secondly, the idea of Expert System (ES) with an updatable rule base is integrated into the testing system. The inputs of ES are the voltage and frequency signals of the key testing point on the laser rangefinder board, and the performance of laser ranging as well. All these are used to make diagnosis on functions and quality of the board, which makes it possible to run efficient tests on the laser rangefinder board indoors.Many experiments prove that the testing system perform well in terms of quality testing and functional verification of the board, as well as its ranging performance evaluation. This system is capable of automatic testing for the mass production of laser rangefinder board.