# DSP System

J

#### Jon Slaughter

Jan 1, 1970
0
How hard is it to actually implement a DSP system?

I've been looking at the TMS320C6720 and some conversion devices and it
seems I can gather all the components needed but I really don't have a good
idea about how to go and implement something like that. The pdf's I've
looked at on TI's don't really go into detail about how to actually put
something together(atleast the one's I've seen).

All I want to do is take an analog signal, add some digital filtering(well,
whatever I want once I get into the software side), and output the signal.

The digital conversion's seems pretty straight forward and I was plan on
using something like the PCM1741 and PCM1807 or something similar for the
conversion(although I ultimately want to go to 192khz).

I think all I'll need is the converters, memory, and the dsp? (I don't think
I'll need a controller?) Is it going to be much harder than just hooking all

At this point I do not need anything fancy and just want to apply some
effects like reverb and chorus to a signal for a start. The biggest problems
at this point is the IC packaging for these devices as most are out of my
reach(BGA, for example) for prototyping.

Is such a conceptually simple project out of my ability as a hobbyist? Do I
need to come up with some prototyping schematic and get some pcb's made for
documents online that can give me some details about the process ;/

Any ideas?
Thanks,
Jon

D

#### David L. Jones

Jan 1, 1970
0
How hard is it to actually implement a DSP system?

I've been looking at the TMS320C6720 and some conversion devices and it
seems I can gather all the components needed but I really don't have a good
idea about how to go and implement something like that. The pdf's I've
looked at on TI's don't really go into detail about how to actually put
something together(atleast the one's I've seen).

All I want to do is take an analog signal, add some digital filtering(well,
whatever I want once I get into the software side), and output the signal.

The digital conversion's seems pretty straight forward and I was plan on
using something like the PCM1741 and PCM1807 or something similar for the
conversion(although I ultimately want to go to 192khz).

I think all I'll need is the converters, memory, and the dsp? (I don't think
I'll need a controller?) Is it going to be much harder than just hooking all

At this point I do not need anything fancy and just want to apply some
effects like reverb and chorus to a signal for a start. The biggest problems
at this point is the IC packaging for these devices as most are out of my
reach(BGA, for example) for prototyping.

Is such a conceptually simple project out of my ability as a hobbyist? Do I
need to come up with some prototyping schematic and get some pcb's made for
documents online that can give me some details about the process ;/

Any ideas?
Thanks,
Jon

What you need is a DSP development board. They will usually contain
all you need to get a project like this off the ground - the DSP chip,
any required memory, a few ADC inputs and DAC outputs etc, many are
targeted specifically for audio use. It's already done for you.
TI have a complete range of them:
http://focus.ti.com/dsp/docs/dspsupporttnp.tsp?sectionId=3&tabId=2079&toolTypeId=1&familyId=44

They aren't particularly cheap, but it can save you weeks of mucking
around with hardware, when really a project like this is all about the
software.

There is nothing really special about DSP's, they are essentially just
a microprocessor with specilised hardware making them faster at math
and signal processing functions than a regular microprocessor or
microcontroller.

Dave.

J

#### Jon Slaughter

Jan 1, 1970
0
David L. Jones said:
What you need is a DSP development board. They will usually contain
all you need to get a project like this off the ground - the DSP chip,
any required memory, a few ADC inputs and DAC outputs etc, many are
targeted specifically for audio use. It's already done for you.
TI have a complete range of them:
http://focus.ti.com/dsp/docs/dspsupporttnp.tsp?sectionId=3&tabId=2079&toolTypeId=1&familyId=44

They aren't particularly cheap, but it can save you weeks of mucking
around with hardware, when really a project like this is all about the
software.

There is nothing really special about DSP's, they are essentially just
a microprocessor with specilised hardware making them faster at math
and signal processing functions than a regular microprocessor or
microcontroller.

I've looked at that but I can justify the expense. Its got, what, about
20-30$worth of components and another 20-30$ for the pcb (if that) yet they
want 400 for just a starter? If theres something I'm missing that makes it
worth it then please let me know about it but it seems like its not worth
it.

Jon

D

#### David L. Jones

Jan 1, 1970
0
I've looked at that but I can justify the expense. Its got, what, about
20-30$worth of components and another 20-30$ for the pcb (if that) yet they
want 400 for just a starter? If theres something I'm missing that makes it
worth it then please let me know about it but it seems like its not worth
it.

Jon

You are paying for the convenience, it's called "starter" for reason,
it gets you started with no with fuss and no wasted effort, productive
from day one.
You might be able to build it for less, but how much is your time
worth?
You have to design your board and get it made, and all the research
that goes along with that. Get the parts in one-off qty that aren't
always available as such. Then you have to sort out the software tools
and libraries etc etc

There are others available, but prices are similar, try this Blackfin
DSP audio kit:
http://www.analog.com/en/prod/0,2877,BF537%2DHARDWARE,00.html

It's got everything you need for audio DSP development, tons of memory
and I/O etc, plus all a whole bunch of software tools.
Digikey have it for $371. Analog devices have other ranges of Audio development kits in their SHARC, TigerSHARC, Blackfin and ADSP-2100 platforms. Dave. D #### David L. Jones Jan 1, 1970 0 I've looked at that but I can justify the expense. Its got, what, about 20-30$ worth of components and another 20-30$for the pcb (if that) yet they want 400 for just a starter? If theres something I'm missing that makes it worth it then please let me know about it but it seems like its not worth it. Jon I forgot to mention that you don't need a DSP for audio processing these days, many of the 16/32 bit processors on the market can easily handle it. You might be able to score a processor development kit with an audio interface for cheaper than the DSP offerings perhaps. Dave. J #### Jon Slaughter Jan 1, 1970 0 David L. Jones said: You are paying for the convenience, it's called "starter" for reason, it gets you started with no with fuss and no wasted effort, productive from day one. You might be able to build it for less, but how much is your time worth? You have to design your board and get it made, and all the research that goes along with that. Get the parts in one-off qty that aren't always available as such. Then you have to sort out the software tools and libraries etc etc Isn't that part of the fun though? I'll eventually have to do that anyways. The only reason I would want the board is so I have some guide lines on how all the components fit together(since I can't seem to find any documentation to help) and because if/when I do it myself I know I'll **** it up and spend days or weeks if not months on some stupid little thing. There are others available, but prices are similar, try this Blackfin DSP audio kit: http://www.analog.com/processors/platforms/ask.html http://www.analog.com/en/prod/0,2877,BF537%2DHARDWARE,00.html It's got everything you need for audio DSP development, tons of memory and I/O etc, plus all a whole bunch of software tools. Digikey have it for$371.

I was just looking at that. It was about 300$direct. The Blackfin seems pale in comparison to the TMS series though. The Shark seems to be decent though. I think I'm just going to try and design a board myself. It may or may not work but I suppose I can post my results here and get a little help. It just seems it will be a few months before I can even start unless I can find some good documentation. The EVM is pretty nice in that it has a bunch of stuff but I don't think I need it all and most likely its overkill. Its nice to have but I wouldn't want to waste 500$(min since I'll need software stuff
too) if I don't follow through with the project I have in mind(although it
would be nice to have around but not for the price).

I'll see what I can come up with though. Trying to gather some info on it
now. The TMS datasheet just didn't give me much hope for finding good info.

Thanks,
Jon

J

#### Jon Slaughter

Jan 1, 1970
0
David L. Jones said:
I forgot to mention that you don't need a DSP for audio processing
these days, many of the 16/32 bit processors on the market can easily
handle it. You might be able to score a processor development kit with
an audio interface for cheaper than the DSP offerings perhaps.

Yes but I think ultimately this is what I want to learn since I have a lot
of projects I would like to eventually work on that involve signal
processing(all audio stuff). Although I was initially planing on doing it
with the pc, I think it will be much more interesting to do it using a DSP
processor(and I think it will be more enjoyable if I'm able to put together
the hardware for it instead of just doing software).

Thanks,
Jon

V

Jan 1, 1970
0
Jon Slaughter said:
How hard is it to actually implement a DSP system?

It depends.
All I want to do is take an analog signal, add some digital filtering(well,
whatever I want once I get into the software side), and output the signal.

If all you need is filtering the audio signal and some effects, the simplest
solution would be a digital audio processor. Consider TAS3004 from TI. It
does have the stereo codec built in. There are also many newer DAPs made by
AD, TI, Cirrus Logic, NXP, AKM and others.
I think all I'll need is the converters, memory, and the dsp? (I don't think
I'll need a controller?)

You will probably need a flash memory.
Is it going to be much harder than just hooking all

Well. The hardest part is to get "some code" to work.
At this point I do not need anything fancy and just want to apply some
effects like reverb and chorus to a signal for a start. The biggest problems
at this point is the IC packaging for these devices as most are out of my
reach(BGA, for example) for prototyping.

Consider buying a DSP evaluation board.
Is such a conceptually simple project out of my ability as a hobbyist?

It is not a rocket science however it requires time and effort, as
everything.
need to come up with some prototyping schematic and get some pcb's made for
documents online that can give me some details about the process ;/

You can use schematic of a DSP evaluation board as a reference.

DSP and Mixed Signal Consultant
www.abvolt.com

D

#### David L. Jones

Jan 1, 1970
0
Yes but I think ultimately this is what I want to learn since I have a lot
of projects I would like to eventually work on that involve signal
processing(all audio stuff). Although I was initially planing on doing it
with the pc, I think it will be much more interesting to do it using a DSP
processor(and I think it will be more enjoyable if I'm able to put together
the hardware for it instead of just doing software).

That hardware is essentially the same regardless of whether you use a
micro, DSP, or FPGA with a processor soft core, the only real
difference is in the speed of processing. In fact FPGA's are becoming
very popular these days for DSP processing, with all sorts of DSP
hardware slices built in to the FPGA fabric, that's where the future
seems to be. But that is a much more difficult learning curve than a
DSP processor.

If you write your code portable enough in C, the bulk of he software
will be the same regardless of the hardware used. You can do the
software development on the PC with a sound card and then port it
fairly easily to your DSP chip and dedicated hardware.

I can appreciate wanting to do the hardware aspect yourself though,
have fun!

Dave.

N

#### Nico Coesel

Jan 1, 1970
0
Jon Slaughter said:
How hard is it to actually implement a DSP system?

I've been looking at the TMS320C6720 and some conversion devices and it
seems I can gather all the components needed but I really don't have a good
idea about how to go and implement something like that. The pdf's I've
looked at on TI's don't really go into detail about how to actually put
something together(atleast the one's I've seen).

I'd choose an Analog Devices. These are much more suitable for general
purpose processing than the TI components. There is also a big user
base and free tools. Just google for Blackfin and gcc.

V

Jan 1, 1970
0
Nico said:
I'd choose an Analog Devices. These are much more suitable for general
purpose processing than the TI components.

I second on the AD DSPs. There is more common sense in the ADI CPU
architecture compared to that of TI. The documentation is more
convenient also.

Yes, for those who like the junk code there is a lot of it.

DSP and Mixed Signal Design Consultant

http://www.abvolt.com

J

#### Jon Slaughter

Jan 1, 1970
0
It depends.

If all you need is filtering the audio signal and some effects, the
simplest
solution would be a digital audio processor. Consider TAS3004 from TI. It
does have the stereo codec built in. There are also many newer DAPs made
by
AD, TI, Cirrus Logic, NXP, AKM and others.

The TAS does not seem to have any DSP like features and the filters are
built in. I need more control because I want to design my own(although
nothing that hasn't been done).
You will probably need a flash memory.

Yeah. TI doesn't seem to make memory? Not sure where to go with that and
not sure if I can find something that is "plug in play"(that isn't going to
require any controllers or anything).
Well. The hardest part is to get "some code" to work.

If you mean from the hardware perspective then I agree(in that I need the
hardware setup properly to get the software to work)... but I'm a lot more
comfortable with coding than I am with building "complex" circuits(its
mainly that a **** up, which I do a lot, is pretty costly in hardware
compared to software).
Consider buying a DSP evaluation board.

I've considered it but I think I'll try and roll my own.
It is not a rocket science however it requires time and effort, as
everything.

You can use schematic of a DSP evaluation board as a reference.

It was something I was looking for but where can I get such a thing?
Specifically for TI as I think I'm more interested in the TMS then anything
else I saw.

Thanks,
Jon

J

#### Jon Slaughter

Jan 1, 1970
0
David L. Jones said:
That hardware is essentially the same regardless of whether you use a
micro, DSP, or FPGA with a processor soft core, the only real
difference is in the speed of processing. In fact FPGA's are becoming
very popular these days for DSP processing, with all sorts of DSP
hardware slices built in to the FPGA fabric, that's where the future
seems to be. But that is a much more difficult learning curve than a
DSP processor.

Yes and that is something else I've been wanting to get into DSP's though
just seem more direct at this point and I have all the stuff to do it(just
not necessarily to do it well). Again, the main issue with the DSP seems to
be the documentation. I guess I just need to spend more time reading it
though.
If you write your code portable enough in C, the bulk of he software
will be the same regardless of the hardware used. You can do the
software development on the PC with a sound card and then port it
fairly easily to your DSP chip and dedicated hardware.

True. The majority of the project is standard stuff though so I think the
main issues are the hardware and dsp specific stuff.
I can appreciate wanting to do the hardware aspect yourself though,
have fun!

I hope

Thanks,
Jon

J

#### Jon Slaughter

Jan 1, 1970
0
Nico Coesel said:
I'd choose an Analog Devices. These are much more suitable for general
purpose processing than the TI components. There is also a big user
base and free tools. Just google for Blackfin and gcc.

Seems though that the components are less powerful for the same price(or
more)? I'll look into it some more though. Just glancing over the
datasheets for the Blackfin was pretty disappointing compared to the TMS. Of
course I'm probably comparing apples and oranges.

Thanks,
Jon

N

#### Nico Coesel

Jan 1, 1970
0
Jon Slaughter said:
Seems though that the components are less powerful for the same price(or
more)? I'll look into it some more though. Just glancing over the
datasheets for the Blackfin was pretty disappointing compared to the TMS. Of
course I'm probably comparing apples and oranges.

Don't just stare at megahertz and mips. AD has a long track record in
DSPs and they know what they are doing. If you want to make a good
comparison, you'll really need to figure out how powerfull the
instruction set is and how well the peripherals unload the CPU by
using FIFOs and DMA.

Some processors may need -say- 10 instructions to perform a certain
operation while others processors may be more clever and only need 1
instruction. If the first processor can do 10mips and the second
processor does 2mips, the second processor will still be twice as fast
as the first.

N

#### Nico Coesel

Jan 1, 1970
0
David L. Jones said:
You are paying for the convenience, it's called "starter" for reason,
it gets you started with no with fuss and no wasted effort, productive
from day one.
You might be able to build it for less, but how much is your time
worth?
You have to design your board and get it made, and all the research
that goes along with that. Get the parts in one-off qty that aren't
always available as such. Then you have to sort out the software tools
and libraries etc etc

If you are going to build your own circuit you'll have to get your
hands dirty and go through all that anyhow. A starter kit is nice, but
the limits are usually reached quite soon (like having no room for
surface mounted components). I mostly design my own starter kits
(based on diagrams from existing starter kits) which only contain what
I really need to evaluate.

J

#### Jon Slaughter

Jan 1, 1970
0
Nico Coesel said:
If you are going to build your own circuit you'll have to get your
hands dirty and go through all that anyhow. A starter kit is nice, but
the limits are usually reached quite soon (like having no room for
surface mounted components). I mostly design my own starter kits
(based on diagrams from existing starter kits) which only contain what
I really need to evaluate.

Have you done anything like this and if so how did you start? The thing I'm
worried about is all the trouble to set it up then miss something. As far as
I see it, its mainly just routing and there are few little things like the
power supply and power issues involved but because I can't seem to find
anything on how to do even a basic dsp I'm worried I'll easily miss a lot of
things ;/ The datasheets only seem to talk about very specific things but
really how to connect the different components. (I do understand most of its
routing but I guess I just need to see what someone else has done and what
works)

Thanks,
Jon

J

#### Jon Slaughter

Jan 1, 1970
0
Nico Coesel said:
Don't just stare at megahertz and mips. AD has a long track record in
DSPs and they know what they are doing. If you want to make a good
comparison, you'll really need to figure out how powerfull the
instruction set is and how well the peripherals unload the CPU by
using FIFOs and DMA.

Some processors may need -say- 10 instructions to perform a certain
operation while others processors may be more clever and only need 1
instruction. If the first processor can do 10mips and the second
processor does 2mips, the second processor will still be twice as fast
as the first.

Sure... I guess if I can find a cheap DSP and some instructions on how to
setup the hardware then I might go with that. Since it would be the first
time its better that I finish than worry about the speed of it. I really
need to spend more time at AD's sight

Thanks,
Jon

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