Is it possible to design Digital Filters (FIR) using CCS C ?

SubhamayS · Joined: 07 Mar 2012 Posts: 34 Location: jalpaiguri, India

I am trying to design digital filters using dsPIC30F/dsPIC33F.

I am referring to the manual provided by microchip http://ww1.microchip.com/downloads/en/DeviceDoc/SW300001%20manual.pdf

Please let me know if it is possible to design FIR / IIR filters using CCS C compiler. I am not able to find any such examples related to this area.

I am using pcwhdupd(CCS 5.015).

please suggest your views on this.

thanks in advance... Smile

Ttelmah · Joined: 11 Mar 2010 Posts: 19535

You don't design the filters with the PIC. The MicroChip note gives you a link to their tool to generate the filter coefficients on a PC. You then just use these in the code you run on the PIC. There are FFT and FIR filter implementations supplied in the examples with the compilers. Even though yours is old they should be there.

temtronic · Posted: Mon Feb 26, 2018 2:17 pm

just a note... that Microchip did have an application note about FFT design using 16/17 series PICs, 20-25 years ago. Yes, it's in assembler BUT the 'math' should be similar or perhaps useful as a basis to cut code in CCS C.

Ttelmah · Joined: 11 Mar 2010 Posts: 19535

For software FFT like this, there have been several threads in the past here. For example:
<http://www.ccsinfo.com/forum/viewtopic.php?t=54587&highlight=fft>

The question here is about using the more powerful features of the DsPIC. CCS do now supply code for this, and it does work, so this has to be the best place to start.

dmendesf · Joined: 31 Dec 2005 Posts: 32

Ttelmah, where you saw support for the DSP features of dspics? This is a long missing feature for me. One that Mikroc implements very well...

Daniel

Ttelmah · Joined: 11 Mar 2010 Posts: 19535

Look at EX_FIR.C and FIR.C include file.

dmendesf · Joined: 31 Dec 2005 Posts: 32

Thanks for the pointers. Still a very crude implementation using ASM directly, but it´s a start.

Ttelmah · Joined: 11 Mar 2010 Posts: 19535

Everything is ASM. C is just a way of writing ASM more easily. The functions are complete and allow a filter to be setup quite efficiently. The only thing is they haven't 'hidden' the ASM from you, but posted it.

temtronic · Posted: Wed Apr 18, 2018 7:49 am

You can also 'cheat' and use the mikeroe website program to create the filter code, then convert into CCS style C.
Also use google to see if anyone else has cut FIR code for dspics....