<< Chapter < Page Chapter >> Page >
This module introduces the design and implementation of IIR filters on the 56002.

Iir filter implementation

The program iir.asm implements a real-time IIR lowpass filter ; the ADC procedure is the same as used for the FIR filter in FIR Filtering . The example IIR filter is found in El-Sharkawy Appendix F, Section 6 . Assemble, link, load and execute this routine; observe the frequency response passband edge frequency using asinewave input to the EVM.

Canonical biquad section

Consider the seven instructions in iir.asm ( shown below ) that implement cascaded second order sections of the IIR filter. For a single section nsec=1 use the flow diagram in and a sequence of diagrams as in to explain the execution of a single biquad section. Express the value of the accumulator at each step interms of x n , w n , and y n .

mpy y0,y1,a x:(r0)+,x0 y:(r4)+,y0 do #nsec,_ends mac x0,y0,a x:(r0)-,x1 y:(r4)+,y0 macr x1,y0,a x1,x:(r0)+ y:(r4)+,y0 mac x0,y0,a a,x:(r0) y:(r4)+,y0 mac x1,y0,a x:(r0)+,x0 y:(r4)+,y0 mac x0,y0,a x:(r0)+,x0 y:(r4)+,y0 _ends
Direct form II canonical IIR second order section.

Filter design

A speech signal has been recorded in the presence of a loud, annoying, high frequency hum. Measurements have indicatedthat the noise energy is isolated to frequencies in the range of 2850Hz to 2950Hz. Use Matlab to design an IIR notch filter to remove these unwanted components. Design the filter for a sampling rate of 16kHz; set the DSP sampling rate to 16kHz in the file ada_init.asm . Implement this filter on the 56002 and verify its operationusing the oscilloscope and speakers. Compare the computational cost of your IIR filter on the 56002 to the FIRdesign from the FIR Filtering Lab .

Matlab suggestions

Use either Butterworth or Elliptic designs with a 'stop' bandreject option. Try a 60dB stopband attenuation as a starting point. Be careful with signs on denominator coefficients. Yourreport should comment on your design choices. Plot both magnitude and phase responses. The reject band can beplotted using these commands:

[h,w]=freqz(b,a,1024); hold off; plot(w*8000/pi,20*log10(abs(h))); axis([2400 3400 -80 0]); grid; hold on; plot([2850 2850],[0 -80],'r'); plot([2950 2950],[0 -80],'r'); xlabel('frequency, Hz'); ylabel('magnitude response, dB');

Saving cycles

Modify your program to avoid the reset of r0 and r1 inside the filtering loop in iir.asm . See Page 165 of El-Sharkawy for comments on modulo addressing and the dsm assembler directive.

Interrupts versus polling

Rewrite your program to implement filtering using interrupts , in contrast to the polling used in iir.asm . The routines within txrx_isr.asm can be modified for this purpose. The main loop of your program should count thenumber of free cycles remaining per sampling period. Use the A accumulator to count the number of cycles not used inimplementing the IIR filter. Store and reset the accumulator value as part of your interrupt routine.

Data structures

Questions & Answers

what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Good
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!





Source:  OpenStax, Filter design - sidney burrus style. OpenStax CNX. May 07, 2009 Download for free at http://cnx.org/content/col10701/1.1
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Filter design - sidney burrus style' conversation and receive update notifications?

Ask