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Megha-
> This is in continuation to my previous mail. I also tried with a breakpoint at my
> next statement after fltoq15. If I run that. It stops in between and gives the
> error:
> Trouble running Target CPU:     Attempted write to ROM at Addr:0x00ffff, Page:0
> I guess it is because of the infinite loop thing. Kindly reply and suggest
> something.Waiting for your reply.

Your code is trying to write somwhere in mem locations 0x8000-0xffff, which are
external Flash as you mentioned before.  Writing directly to Flash area won't work
(although there is a way, which involves a series of Flash chip-specific commands).
You have to check the C code ptr and array address values just before the breakpoint
to see why they are not pointing at onchip or offchip SRAM.

Also, did you see the c55x group thread about IIR cascade fixed-point filters?  I've
included a copy of the latest message below.  If you're not subscribed to the c55x
group, you should.  C55xx devices are the next generation after C54xx -- both 16-bit
fixed-point.

-Jeff
-------- Original Message --------
Subject: Re: [c55x] IIR filter coefficients in iircas5 dsplib
Date: Tue, 16 May 2006 08:37:25 +0200
From: Christian Narvaez <c...@gmx.net>
To: c...@yahoogroups.com

thanks Misan, thanks RK:
indeed this was the problem... I have successfully implemented the
filter now.

CN

nasim ahmed ha scritto:
> hi christian,
>                    u r trying to get q14 fixed point format but dsplib
> has q15 format, i suggest u to use both in same format . u can
> multiply with 2^15 . And two q15 multiplication results q2.30. here 2
> sign bit presents so u hav to modify that according to ur desired
> output format. i hope it will help u , if u hav any prob u can send me
> message.
>
> regards misan
>
> */Christian Narvaez <c...@gmx.net>/* wrote:
>
>     Hi,
>     I am having a problem trying to implement an IIR filter on an TI c55x.
>     I have calculated the filter on matlab getting the following
>     coefficients for 2 second order sections:
>
>     SOS
>     1.0000 1.6854 1.0000 1.0000 -1.7197 0.8565
>     1.0000 -1.9999 1.0000 1.0000 -1.8899 0.9250
>     G
>     1.0000
>     0.1041
>     1.0000
>
>     Simulations perform as expected.
>     Since the coefficients are between ]-2..2[ I transform the SOS matrix
>     as SOS_fix = SOS*2^14:
>
>     SOS_fix
>     16384 27614 16384 16384 -28175 14033
>     16384 -32766 16384 16384 -30964 15155
>
>     The question is: can I run this coefficients on iircas5 of the TI
>     dsplib? I know dsplib is Q.15 while my coefficients are Q.14, but I
>     suppose this is not a problem if the filter's input is small
>     enough not
>     to cause any overflow. Unfortunately this does not work, the
>     output is
>     completely wrong.
>
>     The second think I tried was to multiply the numerator
>     coefficients of
>     the second section of the filter by 0.1041 (according to G), before
>     converting them to Q.14, getting this:
>
>     SOS_fix_G
>     16384 27614 16384 16384 -28175 14033
>     1706 -3412 1706 16384 -30964 15155
>
>     But this also does not work.
>
>     Does anyone have any idea how I should convert my coefficients in
>     order
>     to work with iircas5?
>
>     Thanks.
>
>     Christian

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