Hi!

I have a lot of experience in microcontrollers, but I am a beginner in DSP
world so I would likt some orientation. 
My company is facing a design of a 2mbps modem and I would lika to know
which processors are best suitable for those applications. Some time ago
(/when I wasn't in company) some guy choose a TMS320VC5416PGE dsp processor
from Texas Instruments so the company bought a developement board, etc, etc
and the project whas freezed til now. They told me that project was freezed
because that processor is slow for that application. I would like to choose
the right processor.

Thanks in advance. 
FB

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On Sat, 29 Mar 2008, Franco Bucafusco [Personal] wrote:

> Hi!
>
> I have a lot of experience in microcontrollers, but I am a beginner in DSP
> world so I would likt some orientation.
> My company is facing a design of a 2mbps modem and I would lika to know
> which processors are best suitable for those applications. Some time ago
> (/when I wasn't in company) some guy choose a TMS320VC5416PGE dsp processor
> from Texas Instruments so the company bought a developement board, etc, etc
> and the project whas freezed til now. They told me that project was freezed
> because that processor is slow for that application. I would like to choose
> the right processor.

Before you look at processors, look at your requirements.  Is 2mbps the
thruput or the carrier?  If it is thruput, you need another 1mbps for
handshaking and overhead (at least, more is always better!)  What kinds of
external hardware are you allowed to use - memory mapped on an
address/data bus or serial links?  Or are the signals you have to deal
with already converted from the physical/analog domain to the digital
domain?  How much power can you chew up - is a small battery part of the
requirement or can you be more liberal with power because you are plugged
into mains?

All these requirements will steer you towards different processors - some
are good at lower power, but they cost more too.  They all have different
mixes of periferals as well.  But listing the requirements will help you
eliminate many choices of processors for very simple reasons that they
won't fit one particular need you have.  That usually helps a lot!

One step I like to do is to evaluate the instruction set for some core
process and make a crude guess on how many clock cycles it would take to
the "killer app process".  If one processor stands out that it takes fewer
cycles - it means it can do the task and you might save on power/ emi and
other problems by running slower.  But if you get in a bind - it has the
extra oomf to pull you through.

Every processor is good for something - the main trick is to figure out
how to ensure your requirements fit into somebody elses design.

Patience, persistence, truth,
Dr. mike

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