TMS320C5515: Digital filters in stethoscope application, real-time without latency

V Pot

Expert 1975 points

Part Number: TMS320C5515
Other Parts Discussed in Thread: TLV320AIC3111, TL072, TMDX5515EZDSP, LM386

Hi,

I'm new here. I've been working on developing a digital stethoscope, I've so far worked on analog circuits which consists a preamp, low pass filter and a power amp to drive earphones. I'm having lot of hiss and other background noises in the background. So I turned towards digital filter implementation and looking towards implementing FIR filter or bi-quad to have strict cuttoff frequencies. I came across the article below

digital stethoscope implementation on TMS320C5515. I've following basic questions.

1) can these filters be implemented in real-time without any latency issues? like in the article TI implemented FIR hamming window band pass with order of 161. Can this be run in real-time?

2)do I really require a MCU or DSP like C5515? or can I just use TLV320AIC3111 low power audio codec with digital filtering capability for real time application like stethoscope?

All I need is digital filters like FIR or biquads, and volume control and high power output to drive earphones with low impedance like 24ohms. I would like to stick to the preamp i designed using TL072 opamp.

Thanks in advance

over 6 years ago

0 Cvetolin Shulev-XID over 6 years ago

TI__Guru 65405 points

The team is notified. They will post their feedback directly here.

BR
Tsvetolin Shulev

0 Lalindra Jayatilleke over 6 years ago

TI__Mastermind 30365 points

V Pot,

The C55x DSP might be a good fit for you. There are multiple filtering and DSP functions that are part of C55x DSPLIB which you can peruse.
http://www.ti.com/tool/SPRC100

Here's a quick training module to give you a glimpse on the C55x software offering
software-dl-stage.itg.ti.com/.../

For your questions:
#1. Yes
#2. I would suggest the C55x DSP since you will have a bit more configuration options in software.

Lali

0 V Pot over 6 years ago in reply to Lalindra Jayatilleke

Expert 1975 points

Hi, I appreciate your reply. The training module link is not working.
1)Also I don't have too much expertise into dsp or audio signal processing. Can I get to see the code or filter coefficients used by TI for FIR hamming window band pass with order of 161 in the article above?
2) I'm assuming I would also require an audio codec to work with c55x dsp. what would be your recommendation?
3)There are two different evaluation boards available one is TMDXEVM5515 and TMDX5515EZDSP. which one would you recommend?
Also in future would i be able to miniaturize the setup? I mean just have dsp and codec chips on circuit board. because I need to have everything into a round stethoscope chest piece.

please advise.

0 Lalindra Jayatilleke over 6 years ago in reply to V Pot

TI__Mastermind 30365 points

V Pot,

1) I suggest taking a look at the decimation filter demo in the CSL software-dl.ti.com/.../index_FDS.html located at C:\ti\c55_lp\c55_csl_3.08\demos\decimation\c5515\c55x-digital-mic-decimation

Look in the src directory of this example for filter implementation.

2) www.ti.com/.../TLV320AIC3206

3)Also take a look at the C5545 Boosterpack www.ti.com/.../boost5545ulp. The C5545 is a smaller variant of the C5000 with a 7x7mm package which will suit your small form factor requirement. Look at the specs for each C5000 for what suits you best www.ti.com/.../overview.html

Not sure why the training link isn't working for you. Its working for me.
Does training.ti.com work for you?

Lali

0 V Pot over 6 years ago in reply to Lalindra Jayatilleke

Expert 1975 points

Lali,
yes training.ti.com works for me but not the training link you provided.
1) is there an eval board for aic3206 to use with c5545 booster pack? can this audio codec drive my low impedance earphones with loud heart sound or do i require to have a lm386 power amp after the codec output?
2)are c5515 and c5545 same in terms of software implementation and stuff?

0 Lalindra Jayatilleke over 6 years ago in reply to V Pot

TI__Mastermind 30365 points

V Pot,

You can search for "c55x dsplib" at training.ti.com and the module should come up.

1)The C5545 Booster pack has an onboard AIC3206. Please see the schematics for the board www.ti.com/.../sprr233
Please check on the e2e.ti.com/.../64 forum. The experts there can answers specifically on the codecs.

2)Yes, similar. The CSL I pointed to above supports both devices.

Lali

0 V Pot over 6 years ago in reply to Lalindra Jayatilleke

Expert 1975 points

Thank you Lali,
I'll talk to codec guys for further information on codec specifications. You've been a great help. I'll order the booster pack on TI and give it a try. If I have any issues i'll shoot you a message.

0 V Pot over 6 years ago in reply to Lalindra Jayatilleke

Expert 1975 points

i looked into the decimaion fiter thing, that is for mems. im using ecm mic. Also I was asking for FIR hamming window band pass with order of 161 filter code used by TI in the article below , page 13.
www.ti.com/.../sprab38a.pdf

0 Lalindra Jayatilleke over 6 years ago in reply to V Pot

TI__Mastermind 30365 points

V Pot,

There are various filters provided in the C55x DSPlib which has information here processors.wiki.ti.com/.../C55x_DSPLIB_FAQ
MEMs mic is the only reference code we currently have as part of the application note I pointed to earlier with decimation.

Lali

Processors

Processors forum

TMS320C5515: Digital filters in stethoscope application, real-time without latency