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DSP development recommendations?
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Author DSP development recommendations?
intellijel
I really want to start experimenting with a simple DSP system and there are a lot of choices.

My embedded system experience has mainly been with 8bit microcontrollers so working with DSP chips will be pretty new ground for me.

Any recommendations?


dsPIC?
Xmega?
Spin?
Arturo00
Bump. I'm wondering the same thing. Anyone? Anyone?...Anyone?

Danjel, did you figure anything out? Care to share?

thx.
Neutron7
I got the development board from spin semiconductor, which is a simple DSP with 2 audio in and 2 audio out and 3 potentiometer controls.

unfortunately the pot controls only get polled 100 times a second, so you can not use them for audio rate voltage control.

It is not DSP but the "maple" from leaf labs is a 32 bit ARM board that can do 90MIPs and it is (mostly) arduino compatible. (and has 12 bit ADC/DAC instead of 10 bit) i have one on order.

i wish someone would embed ARM + DSP and put it on a board like that!
6.4 Billion
I believe most of the arm cortex m3 variants have dsp libraries available from their vendors.
Arturo00
Thanks Neutron7! I saw some of your DIY stuff a few weeks back. Looks really really good!

I'll look into your suggestions.
det3
Another thing to note is that Freescale has their Soundbite development board for 563xx series DSPs:

soundbite product page

They're US$150. Not bad for a board that has the same processors that run the Microwave series, the Virus, and many other audio products.
Neutron7
det3 wrote:
Another thing to note is that Freescale has their Soundbite development board for 563xx series DSPs:

soundbite product page

They're US$150. Not bad for a board that has the same processors that run the Microwave series, the Virus, and many other audio products.


that is very cool, since it has 4 audio inputs, they could be used for control voltages. although it is probably not DC coupled. you could do a LOT with that!

question is, whats the programming environment like, and do they charge Ti type price for it? i saw there was a c example, thats a good sign
Arturo00
Neutron7 wrote:
question is, whats the programming environment like, and do they charge Ti type price for it? i saw there was a c example, thats a good sign


This was the first paragraph from the link provided by det3:

Freescale introduces the Symphony SoundBite Development Kit, designed for cost-sensitive applications and college laboratories, providing a very low-cost entry point into high-end DSP solutions.

So hopefully their idea of low-cost is on par with ours 8_)
det3
Okay, I'm going to go a bit further forward here and give some opinions.

IMHO, the Freescale architecture is not the best in the realm of DSPs. It's 24-bit fixed point which means when doing things like high-gain summing nodes and filters you will have to pay careful attention to saturation and clipping. Analog Devices and Texas Instruments have better silicon, and somewhat better tools. What makes the Freescale architecture more popular for most purposes is that there is a full development toolchain available for free, combined with low cost development hardware like the SoundBite.

This doesn't mean the 563xx architecture is bad - it's well suited to 80% of most DSP applications for 20% of the cost of a comparable SHARC or TI solution.

Back on topic! The replacement to the old Suite56 compiler is now called Symphony Studio. It's built on GCC technology and wrapped in a nice IDE based on Eclipse. It's free, and unrestricted for developing applications on the 56K architecture.
skrasms
Almost every DSP module I've seen so far has had a dsPIC in it. The one exception is the Spin Semi part TipTop is using. If you buy any dsPIC tools, I'd recommend getting stuff from Microchip. Back when I used dsPIC, I made the mistake of getting some third party stuff with a buggy compiler and no resale value.

An important question is how easy you want things to be. I won't touch a Spin chip because it requires Assembly for everything. If I'm going to go that low level, I would just use an FPGA and write Verilog (even a small FPGA can obliterate the DSP horsepower of a dsPIC or that Spin chip). With a dsPIC you can write C code, which is a big time saver.

dsPIC is getting a little old these days, and it's only 16-bit (though with a 40-bit accumulator). Looking to the future, Cortex M3 is the new inexpensive ARM standard (replacing ARM7TDMI). STM32 parts are a cheap option there (cheap as in starting at a few dollars each in single piece quantities), and there are free C development tools that don't take hours to setup. I've been playing around with Atollic Truestudio. Even the free version has no code size limit and works great.

Unlike a dsPIC, Cortex M3 parts don't have a wide accumulator or a MAC instruction with memory prefetching and all that. However, they also doesn't need four cycles per instruction like a dsPIC. Depending on what you're doing, and how much you actually use Assembly-based MAC operations compared to others, an M3 part can perform quite well in comparison.

Cortex M4 parts get into actual DSP hardware + M3 hardware, but they're only just coming out and look expensive. Some M4 parts are promising floating point hardware, which is easier to work with than fixed point. With floating point, for example, you don't have to worry about IIR stability issues caused by truncation in fixed point filter coefficients. You also don't need to constantly "normalize" the calculations to reduce errors as in fixed point because the floating point barrel shifter takes care of that for you. These advantages make it much more transparent for development. The math just works out with less work. There are some algorithms where fixed point wins (such as CIC filters), but that's getting pretty deep.

I don't know much of anything about Freescale. I pretty much jumped from dsPIC hardware to FPGAs and SHARCs. For inexpensive stuff I'm looking at STM32.
dude
i use a SHART processor
skrasms
dude wrote:
i use a SHART processor


You have to be careful with those. I've heard they can be quite explosive.
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