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Which DSP should i be using?

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Antonio_Magma

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Hi guys,

I'm currently in the beginning phase of my project of design and implemention of a prototype OFDM powerline modem.

I'm currently looking for a DSP which can perform the basic operations of OFDM and the normal AD/DA conversion serial/parallel conversion those kind of stuff.

I've looked at sites such as ti.com and there are so many of them. Is there any DSPs out there that you guys recommend? What should i be looking for? Coz i'm a beginner with all these hardware stuff and the technical specifications are totally driving me nuts.

I am looking for an evaluation kit and i'm quite tight on my budget.
 

eltonjohn

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look at the C2000 family . Is a matter of much processing power you need .
Then look for one that matches your need
Also take a look at the DspPic family .
 

Antonio_Magma

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Are all models in the C2000, C5000 & C6000 family capable of IFFT and FFT? Because if they are, it will only be the matter of choosing the cheapest one. Are all DSPs capable of IFFT and FFT or only the specific ones?

Because frankly speaking i do not know how much power or what kind of specifications i need. All i need is a basic and cheap model which can perform OFDM modulation and demodulation
 

penrico

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I think C2000 is most suitable for you, it have a ADC and PWM to receive and create the signal. C5000 and C6000 don't have ADC and PWM, it need and external converter or codec.

C24xx are up to 40 MIPS, in 16 bits
C28xx are up to 150 MIPS in 32 bits

I used both and works ok, you must see if 40 MIPS 16 bits are enogth to your project, then jump to C28xx if it's not. If you want to be sure start with C28xx, and then optimize and go down to C24xx.

DSPics are up to 30 MIPS and 16 bits.

Good luck
 

Antonio_Magma

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Thx man, at least i have a direction now...
 

Antonio_Magma

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penrico said:
I think C2000 is most suitable for you, it have a ADC and PWM to receive and create the signal. C5000 and C6000 don't have ADC and PWM, it need and external converter or codec.

C24xx are up to 40 MIPS, in 16 bits
C28xx are up to 150 MIPS in 32 bits

I used both and works ok, you must see if 40 MIPS 16 bits are enogth to your project, then jump to C28xx if it's not. If you want to be sure start with C28xx, and then optimize and go down to C24xx.

DSPics are up to 30 MIPS and 16 bits.

Good luck

I think i have more or less decided on using F2812, however since it only has ADC i suppose at the reciever side i'll have to perform the DAC on another module, right?
 

orthogonal

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I think it is depend on the speed of your PL modem.
 

the_jackal

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The C6x does infact have an ADC and a DAC. there is an onboard codec AD535 which uses a sigma-delta technology that provides ADC and DAC.
 

penrico

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Antonio_Magma said:
penrico said:
I think C2000 is most suitable for you, it have a ADC and PWM to receive and create the signal. C5000 and C6000 don't have ADC and PWM, it need and external converter or codec.

C24xx are up to 40 MIPS, in 16 bits
C28xx are up to 150 MIPS in 32 bits

I used both and works ok, you must see if 40 MIPS 16 bits are enogth to your project, then jump to C28xx if it's not. If you want to be sure start with C28xx, and then optimize and go down to C24xx.

DSPics are up to 30 MIPS and 16 bits.

Good luck

I think i have more or less decided on using F2812, however since it only has ADC i suppose at the reciever side i'll have to perform the DAC on another module, right?


Use PWM and a low pass filter to make the DAC.
 

zhaoyimiao

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You need to estimate the MIPS cost first. OFDM may need high speed IFFT and channel codec and other signal processing unite such as equalizer. So it is better to choose a very powerful one. ADI also have some DSPs like blackfin shark.
 

Antonio_Magma

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Thx zhaoyimiao,

but i'm currently still in my literature and theory research phase, so my problem is that i don't know how to determine what can of speed or power do i need, or what data rates am i expecting and the N number of FFTs/IFFTs. My supervisor says to be safe, he suggest to go for the C6000 models.

Or if you could give me an example? Like, for a 256 FFT how much data rate are we looking at and the MIPS required? Do i have to consider on-board memory?

Btw, Flash and ROM? What are their advantages and disadvantages?
 

swahlah

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Dear Antonio_Magma,
I will recommend you to see the Phillips Nexperia family too. I think PNX 1500 is also useful for you task. Recently PNX1700 is also in market.
But PNX 1500 is a low cost solution so if you have less budget then i will recommend you to go for phillips processor family which is low cost DSP and also it has lots of resources useful for your work ADC, MBS, QVCP and the core VLIW Processor

Think about this you can get further details from phillips site.

Sincerely,
 

penrico

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Hey,

I found this:

**broken link removed**

Be carefully, it say thats for OFDM you will need more than 4000 MIPS.... So it's impossible to put nowadays in a single DSP.
 

Antonio_Magma

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thx penrico, but i guess i wont b implementing viterbi decoding...mine is only an prototype implementation
 

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