pyFDA

pyFDA is a graphical program for designing digital filters. You choose a method such as equiripple, window, Butterworth, Chebyshev, elliptic or Bessel, set the order and corner frequencies, and immediately see magnitude, phase and group delay responses, a pole-zero diagram and the response to an impulse, a step or a stimulus of your choice. You can check fixed-point behaviour, overflow and quantisation before implementing on an FPGA or microcontroller, and export coefficients to CSV, Matlab, CMSIS and Xilinx COE. It suits students and signal processing engineers. Limitation: it is a single-developer project, and some Linux packages do not always work.