Tips on what MCU/DSP to use

c_ 64

Other Parts Discussed in Thread: TMS320C5535, TMS320C5515

Hi,

I wasn't really sure what specific group I should post this in, so I'm taking a chance with this one. What I'm looking for is some advice/tips on what MCU or DSP I should use for my application and needs. These are some of what I am looking for:

1) Capabilities of doing FFTs and IFFTs quite fast. I bought the Piccolo a while ago, but it takes about 7 ms for an FFT. I looked at a competitor's website, where they report that the dsPIC33E, for instance, does a 256 point complex FFT in 280 us (using their DSP library). I may not need something that fast, but it sure is a good benchmark.

2) At least two ADCs for sampling.

3) A DAC for generating a signal to a VCO (my application involves an FMCW radar sensor). This ruled out the Piccolo, because as far as I could see, its DACs were only for PWM.

4) Low power. This is obviously relative, but the Piccolo consumes too much power, as a reference.

5) Ease of use with DSP libraries. I am not a microprocessor expert, nor a software engineer, and I find myself spending a lot of time getting things up and going. I'm therefore looking for software tools and libraries that are easy to use, and as close to plug'n'play as possible. As a side note, I tried the Arduino a while back, for something else, and I was amazed by how easy it was to use and get going.

Thanks!

over 13 years ago

0 Steve Tsang over 13 years ago

TI__Mastermind 23785 points

Take a look at the C55 family of products.

If you don't need external memory interface, use the low cost C5535.

http://www.ti.com/product/tms320c5535&lpos=See_Also_Container&lid=Alternative_Devices

The C5515/05 have EMIF interface.

http://www.ti.com/product/tms320c5515

There is internal FFT hardware accelerator, ADC, low power and C55 library.

Regards.

0 c_ 64 over 13 years ago in reply to Steve Tsang

Intellectual 630 points

Thank you. I took a quick glance, but I can't seem to find a Digital to Analog converter for my external VCO. Am I missing it?

0 Steve Tsang over 13 years ago in reply to c_ 64

TI__Mastermind 23785 points

Sorry. No D to A. Only A to D.

0 c_ 64 over 13 years ago in reply to Steve Tsang

Intellectual 630 points

Ah well, I need a DAC. What devices would you recommend then?

0 Mark M over 13 years ago in reply to c_ 64

TI__Mastermind 30140 points

All of our EVMs include an off-chip AIC3204 IC - audio quality delta-sigma DAC/ADC - .

They are typically used for sampling audio/voice, but could be used for many signals.

Check out the C5535 eZdsp.

Hope this helps,
Mark

0 c_ 64 over 13 years ago in reply to Mark M

Intellectual 630 points

Ok, I'll look into that. Btw, do you happen to know how fast a C5000 can perform a, say, 256 point complex FFT with the DSP libraries that TI provide? It would be interesting to compare these numbers with other vendors.

0 Mark M over 13 years ago in reply to c_ 64

TI__Mastermind 30140 points

Hi,

See Table 4. FFT Performance on HWAFFT vs CPU (Vcore = 1.3 V, PLL = 100 MHz) in SPRABB6 (http://www.ti.com/lit/an/sprabb6a/sprabb6a.pdf)

This table compares execution cycles for complex FFTs in DSPLIB vs complex FFTs with the on-chip FFT hardware accelerator.

DSPLIB 256-pt CFFT + Bit Reverse takes 5947 cycles = 59.5uS @ 100MHz

HWAFFT 256-pt CFFT + Bit Reverse takes 1668 cycles = 16.7uS @ 100MHz

HWAFFT is 4 to 6 times more energy efficient and 2.2 to 3.8 times faster than the CPU running DSPLIB.

Regards,
Mark

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Tips on what MCU/DSP to use