The Research Of Ultrasonic Range Finder Based On DSP MC56F8037

As one of the nondestructive test (NDT), the system of ultrasonic ranging is not affected by the light, color and the material, it also has certain ability to adapt to the environment, the next advantages are high frequency, short wavelength and small diffraction phenomenon, especially the good direction. This makes the ultrasonic ranging system used in industrial automation non-contact link, the water-saving irrigation of agricultural water conservancy engineering, the reversing radar of automotive safety, and other fields. However there are some problems in practical application about ultrasonic ranging,so we need further research in how to improve the measurement range and precision aspects.This combined the DSP technology and ultrasonic ranging technology to develop a ultrasonic range finder whose the measuring range is0.5～7m and accuracy is2cm. Using DSP MC56F8037developed by the freescale company as the core of the microprocessor system, first of all, using it to produce26KHZ PWM wave excitation, the PWM wave through the logic circuit and high-frequency transformer converts to the high frequency high voltage signal to drive the ultrasonic probe of launch ultrasonic wave; Due to this design uses the one-piece ultrasonic probe conbined sending and reciving, the probe will transfer the weak induced ultrasound echo signals to the DSP via the hardware control circuit. The DSP deal with the acceptable signal automatically and calculate the distance, then refresh the distance in real time and display it by LCD. According to the design requirements, the main research targets and contents are the design of hardware structure and the development of software engineering.Hardware circuit mainly uses the high-speed and elatively inexpensive MC56F8037DSP as processor, and it enhanced the processing capacity for echo signal and the stability of the system compared with the general single chip as the processor for ultrasonic rangefinder system. Also includes power module, ultrasonic transmitting module, the receiving signal processing module, temperature compensation module, man-machine interface (LCD display), etc.1) power supply modules:including the+12V voltage regulator output circuit, plus or minus5V dc voltage output circuit,+3.3V dc voltage output circuit.2) ultrasonic emission module:includes logic driver module, push-pull transmitter, high frequency transformer.3) ultrasonic signals processing module, including limiting circuit, preamplifier circuit, pass filter circuit, the output precision rectifier circuit, voltage reference circuit, compare circuit, the RS trigger circuit. 4) temperature compensation module:biggest error sources of ultrasonic ranging is the influence of environment temperature on ultrasonic transmission speed, in order to obtain more accurate measurement results, using the empiricalformula V=331.5+0.61T for temperature compensation.Software system design makes full use of internal resources to realize the DSP MC56F8037range of each function, mainly includes the following parts:the main program, A/D conversion subroutine, temperature compensation subroutine, distance calculation program, communication module and liquid crystal display subroutine, the main program to complete the program initialization and ultrasonic emission control.