A New Decoding Logic for Quadrature Encoder Interfacing for Software Implementation on FPGA

This paper presents a new method for decoding the signals from the input channels of the encoder into determining the states and the changes of the encoder input from one state to another. Since it is a quadrature encoder it has specific states related to encoder position and the changes of states from one specific state to another will give the direction of rotation. A present state-past state table has been constructed based on the inputs of the encoder and a logic function has been developed. The program will evaluate that equation and determine the direction of the rotation as well as to count the number of times the states of the input has changed to get the estimated amount of rotation. The simulation results are provided in this paper.