This source code is under MIT License
The library files consists of libpid.c and libpid.h files. The libpid files consists implementation of pid controller algorithm in c programing language. It consists of derivative filter, antiwind up schemes, and forward, backward Euler and trapizoidal method of continous to digital conversion. or (s->z) mapping.
All the rest files test.c is example how to use the functions. It is not necessary to model your plant in main function as done in test.c. The response1.bmp, response2.bmp, response3.bmp shows the ac and step response of plant with pid controller. All graphs are plotted using gnuplot.