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This module is the exercise to implement FIR filtering in TI TMS320C62x assembly.

Implementation of fir filters in assembly

Storing filter coefficients

Rather than defining the filter coefficients in your main assembly program file, it is usually more convenient tostore them in a separate file. By defining the coefficients in a separate assembly (for example, coeff.asm ) file, you can load the coefficients at a desired memory location at the run time,although it is not essential for the current simple FIR filtering lab.

The assembly file containing the filter coefficients can be written as follows:

.def _coef .sect "coeffs" _coef: .short 0ff9bh .short 0ff06h .short 0feffh .short 0ff93h .short 070h .short 0117h .short 0120h .short 07bh

Each coefficient must be converted to the Q-15 format and defined by each .short assembly directive. For your convenience, I wrote a short MATLABscript save_coef.m that converts the filter coefficients stored as a MATLAB vector to Q-15 format andthen writes to a file exactly in the above format. (You can download save_coef.m from the course web page.) The section coeffs should be defined in the link command file so that the coefficients are tobe loaded at the correct memory location.

You can simply include the coeff.asm using the .include directive at the beginning of your main assembly program.

Make coefficient files for each of the filters you designed in the previous exercise.

Assembly implementation

Based on the codec input and output program you have written in the previous labs, you can now implement areal-time FIR filtering algorithm.

Write an assembly routine that implements the FIR filter by modifying the inner product program you havewritten in Lab 3. Combine the FIR filtering routine with the interrupt-based codec input-output code youwrote in the previous lab. Your code should perform FIR filtering on the input samples and output thefiltered result to the codec. Both the left and right channels should be filtered. To write the designedMATLAB vector of filter coefficients as a .asm file, use the provided save_coef.m matlab function. First implement the length-40 lowpass filter with 10kHzcutoff designed using the remez.m .

Implementation using circular addressing modes

As you might already have noticed, a lot of cycles are wasted in FIR filtering while maintaining the buffer tosee if you reached the end of buffer and update the address pointers properly. To avoid this unnecessarybuffer maintenance, the TI DSP processors have a special addressing mode, called circular addressing . Using circular addressing, you can define a block ofmemory as a circular buffer. As you increase (or decrease) the pointer register pointing to the buffer index beyondthe buffer limit, it automatically points to the other end of the buffer, implementing a circle of data array.Instead of moving the data samples themselves, you can move the pointer which specifies the beginning of thebuffer, as each new sample is processed. You don't need to check if you reached the end of buffer because the addresspointer returns to the beginning of the buffer immediately after reaching the end.

Of the 32 registers on the C6x, 8 of them can perform circular addressing. These registers are A4 through A7and B4 through B7. Since circular addressing is not default, each of these registers must be specified ascircular using the AMR (Address Mode Register) register. The lower 16 bits of the AMR are used to select the mode for each of the 8 registers. The upper 10 bits (6 are reserved) areused to set the length of the circular buffer. Buffer size is determined by 2 N 1 bytes, where N is the value appearing in the block size fields of the AMR register. The top address of the buffer needs to be aligned with proper physical memory blockaddress using the .align assembler directive.

First read TMS320C62x/C67x CPU and Instruction Set Reference Guide to learn how to define circularbuffers. Modify your FIR filtering assembly code to use circular addressing modes. After optimizing yourcode as much as you can, count the number of required clock cycles for each FIR filter outputcomputation. Compare the number with the code written without circular addressing.

Questions & Answers

what is math number
Tric Reply
x-2y+3z=-3 2x-y+z=7 -x+3y-z=6
Sidiki Reply
Need help solving this problem (2/7)^-2
Simone Reply
x+2y-z=7
Sidiki
what is the coefficient of -4×
Mehri Reply
-1
Shedrak
the operation * is x * y =x + y/ 1+(x × y) show if the operation is commutative if x × y is not equal to -1
Alfred Reply
An investment account was opened with an initial deposit of $9,600 and earns 7.4% interest, compounded continuously. How much will the account be worth after 15 years?
Kala Reply
lim x to infinity e^1-e^-1/log(1+x)
given eccentricity and a point find the equiation
Moses Reply
12, 17, 22.... 25th term
Alexandra Reply
12, 17, 22.... 25th term
Akash
College algebra is really hard?
Shirleen Reply
Absolutely, for me. My problems with math started in First grade...involving a nun Sister Anastasia, bad vision, talking & getting expelled from Catholic school. When it comes to math I just can't focus and all I can hear is our family silverware banging and clanging on the pink Formica table.
Carole
I'm 13 and I understand it great
AJ
I am 1 year old but I can do it! 1+1=2 proof very hard for me though.
Atone
hi
Adu
Not really they are just easy concepts which can be understood if you have great basics. I am 14 I understood them easily.
Vedant
find the 15th term of the geometric sequince whose first is 18 and last term of 387
Jerwin Reply
I know this work
salma
The given of f(x=x-2. then what is the value of this f(3) 5f(x+1)
virgelyn Reply
hmm well what is the answer
Abhi
If f(x) = x-2 then, f(3) when 5f(x+1) 5((3-2)+1) 5(1+1) 5(2) 10
Augustine
how do they get the third part x = (32)5/4
kinnecy Reply
make 5/4 into a mixed number, make that a decimal, and then multiply 32 by the decimal 5/4 turns out to be
AJ
how
Sheref
can someone help me with some logarithmic and exponential equations.
Jeffrey Reply
sure. what is your question?
ninjadapaul
20/(×-6^2)
Salomon
okay, so you have 6 raised to the power of 2. what is that part of your answer
ninjadapaul
I don't understand what the A with approx sign and the boxed x mean
ninjadapaul
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
Salomon
I'm not sure why it wrote it the other way
Salomon
I got X =-6
Salomon
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
ninjadapaul
oops. ignore that.
ninjadapaul
so you not have an equal sign anywhere in the original equation?
ninjadapaul
hmm
Abhi
is it a question of log
Abhi
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Abhi
I rally confuse this number And equations too I need exactly help
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But this is not salma it's Faiza live in lousvile Ky I garbage this so I am going collage with JCTC that the of the collage thank you my friends
salma
Commplementary angles
Idrissa Reply
hello
Sherica
im all ears I need to learn
Sherica
right! what he said ⤴⤴⤴
Tamia
hii
Uday
hi
salma
hi
Ayuba
Hello
opoku
hi
Ali
greetings from Iran
Ali
salut. from Algeria
Bach
hi
Nharnhar
A soccer field is a rectangle 130 meters wide and 110 meters long. The coach asks players to run from one corner to the other corner diagonally across. What is that distance, to the nearest tenths place.
Kimberly Reply
Jeannette has $5 and $10 bills in her wallet. The number of fives is three more than six times the number of tens. Let t represent the number of tens. Write an expression for the number of fives.
August Reply
What is the expressiin for seven less than four times the number of nickels
Leonardo Reply
How do i figure this problem out.
how do you translate this in Algebraic Expressions
linda Reply
why surface tension is zero at critical temperature
Shanjida
I think if critical temperature denote high temperature then a liquid stats boils that time the water stats to evaporate so some moles of h2o to up and due to high temp the bonding break they have low density so it can be a reason
s.
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris Reply
where are the solutions?
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Source:  OpenStax, Finite impulse response. OpenStax CNX. Feb 16, 2004 Download for free at http://cnx.org/content/col10226/1.1
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