In this exercise, you will program in the DSP's assembly language to create FIR filters. Begin by studying the assembly code for the basic FIR filter filtercode.asm. For help with circular addressing, view Addressing Modes for TI TMS320C55x.
| filtercode.asm |
|---|
|
filtercode.asm applies an FIR filter to the signal
from input channel 1 and sends the resulting output to output
channel 1. It also sends the original signal to output
channel 2.
First, create a work directory on your network drive for the
files in this exercise, and copy the filter folder from
v:\ece420\55x\ccs4\filter to your work directory. Then, use MATLAB
to generate two 20-tap FIR filters. The first filter should
pass signals from 4 kHz to 8 kHz; the second filter should
pass from 8 kHz to 12 kHz. For both filters, allow a 1 kHz
transition band on each edge of the filter passband. To
create these filters, first convert these band edges to
digital frequencies based on the 48 kHz sample rate of the
system, then use the MATLAB command firpm to
generate this filter; you can type help firpm for
more information. Use the save_coef command to
save each of these filters into different files. (Make sure
you reverse the vectors of filter coefficients before you save
them.) Also save your filters as a MATLAB matrix, since you
will need them later to generate test vectors. This can be
done using the MATLAB save command. Once this is
done, use the freqz command to plot the frequency
response of each filter.









"Real-Time DSP with MATLAB"