design of simple low pass filter

i want to design a single butterworth low pass filter which order is n=2;cutoff frequency=20hz,damping coefficient=1;sampling frequency=1000hz.i did it in simulink block.can it possible to write in MATLAB code?is this code can be transformed into assembly language?can anyone help me regarding this.thank you.

[Jan]

The cut-off frequency must be expressed relative to the sample freuqency. When the order, cut-off frequency and type of the filter (Butterworth) is fixed, the damping coefficient can not be chosen anymore.

Answer 1

[Jan]

Have you seen this thread: http://www.mathworks.com/matlabcentral/answers/73918-filter-coefficients-for-butterworth-low-pass-filter ?