基于FPGA的EnDat协议绝对式光栅尺通讯实现

Realization of EnDat Protocol Absolute Grating Ruler Communication Based on FPGA

为了满足高速精密运动控制对光栅尺信号的实时反馈的要求,设计了基于FPGA的EnDat 2.2协议接口模块和上位机。针对EnDat 2.2协议的通信传输方式及光栅解码要求,采用状态机设计了解码模块,并通过Modelsim仿真工具验证时序。利用FPGA和MAX485模块组成硬件电路,通过解码模块和CRC校验模块对光栅尺信号进行数据处理,最后把解码并验证成功的位置和参数信息通过串口发送到上位机显示。仿真与实测结果表明该数据采集系统位置采集周期小于40μs,能够满足25 kHz的控制要求,并且成功发送位置值到GUI上位机显示。

In order to meet the requirements of real-time feedback for grating scale signal in high-speed precision motion control, the interface module of EnDat 2.2 protocol based on FPGA and the host computer were designed.According to the communication transmission mode grating decoding requirements of the Endat 2.2 protocol, the decoding module was designed through the state machine, and time sequence was verified by Modelsim.The hardware circuit composed of FPGA and MAX485 module was used to cooperate with decoding module and CRC check module to process the grating ruler signal.Finally, the decoded position and parameter information were sent to the host computer through serial port for display.The simulation and measured results show that the position acquisition period of the data acquisition system is less than 40 μs, which can meet the control requirements of 25 kHz, and can send the position value to the GUI host computer for display.