Design Of Absolute Encoder For SSI Protocol Based On CPLD

Grating encoder with high efficiency,easy to control,good performance and other characteristics,has a wide range of applications in the CNC machine tools field,industrial field,aerospace field.In recent years,with the continuous innovation of automation control technology,grating encoder plays a very important role in in the position,speed control and debugging process,so its application is increasing,mostly used in complex industrial environments.At present,it is an important measurement and control equipment in the field of automation and control.With the increasing demand for equipment,the research of grating encoder will become a hot spot.In order to reduce the gap with foreign countries,China has increased the investment in the key technology of grating encoder,opened up a broad market areas.Grating encoder has become an indispensable component in modern industrial field,and its quality is directly related to productivity.In order to meet the needs of market and industry,absolute encoders gradually replace the incremental encoder,and it is also constantly improving and developing in the communication technology,which uses SSI protocol communication is the most extensive way.In order to improve the accuracy of the measurement,it is necessary to convert the output of displacement or angle value into the corresponding digital signal,so the study of the encoder has great practical significance.According to the above-mentioned problems,this paper presents a design scheme of absolute encoder for SSI protocol based on CPLD,through the verification analysis,it can realtime receiving grating encoder output of A,B and Z signals,and these signals are shaping filter,frequency multiplication phase,reversible counting,and SSI output and so on,eventually it can get location information through the number of pulses.First of all,the paper elaborates the background of the topic,the research status at home and abroad and the working principle of grating encoder.Then according to the requirements of the functional design,this paper describes CPLD chip selection,builds hardware platform,gives the entire system design,and introduces the design idea of main modules in detail,the received signal of the grating encoder is shaping,filtering,subdividing by CPLD chip,frequency multiplication phase,counting,SSI signal processing,the use of Verilog HDL hardware language to achieve the function of each module,with Quartus II software to compile and simulate,the accuracy of the CPLD design has been verified.Finally,from two aspects respectively of hardware and software verification and testing,and constantly improve the program.Compared to the earlier design scheme,the result proves that the system is stable and reliable,strong anti-interference,good performance and potential market value,which is of great significance to promote the development of industrial control automation in China.