DSPs Vs. FPGAs Vs. Microcontrollers for uni project

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DSPs Vs. FPGAs Vs. Microcontrollers for uni project

Post by TRONICLK » Sun Mar 25, 2012 9:48 pm

Since it is restricted to ask or answer technical questions in private messages, I'm going to answer Yurihalo in public since it is useful for anybody who's starting with these embedded platforms.
On some posts on this forum i got to know that it would be better to get some advice from you regarding fpga, dspic applications since you are knowledgeable on this topic. what i have to do fro a certain project is to grab audio or pressure using 6 piezo electric sensors as either audio pickups or force sensors process them and give an audio output. regarding the processing part the project (when considering the worst case scenario), it would require processing the audio from 6 piezo pickups (fft should be performed on all the inputs ) and then depending on the fourier spectrum a new 2 channel audio output is given. so would a dspic alone be capable of doing this or would an fpga dspic combination be cpable of doing this or would i have to consider DSP processors?

this is why i was asking whther you had fpga or dspic30f4011(this was recommended by a member on this forum for audio applications if you have any better component in your mind please do suggest).
I'll give you a good answer based on my experience. I personally worked with DSPs, FPGAs and uCs. DSPs are very good but it is expensive to give a start with DSPs. Most of the time you will have to buy the evaluation module (it is not easy to make one by yourself like for uCs), JTAG emulation module and Code Composer Studio (CCS) software (60-day trial in available). All these are not easy and worth to afford for a single project. This is where most of the people are struck. If there is an investor for you or your university is willing to invest for the project, we can offer you a suitable EVM, JTAG and CCS. But it would be not less than $4000 to start with. DSPs are made to perform advance calculations such as FFTs, DCTs, FIRs, IIRs, etc... DSPs mostly have multiple execution paths (parallel processing) to do several calculations at ones, not just one at a time like in most uCs.

If you take FPGAs, those are devices to do specific tasks. In other words, an FPGA is suitable to do a quick processing of output based on set of inputs. So for fixed algorithms such as FFTs, an FPGA can help. However FPGA is not a cheap and easy to make solution. If you like to work on an Altera FPGA, you can buy an evaluation module, byteblaster unit and use the free IDE to program them.

Finally the uCs (microcontrollers). There are two popular manufacturers, Microchip and Atmel. The main microcontroller product series is called PIC. dsPIC is kind of an advance microcontroller with Digital Signal Processing capabilities. Atmel is well known for stability and reliability. They have two popular product lines called ATTiny and ATMega.

Since you application is more biased on Digital Signal Processing (such as application of FFTs, etc..), the best I can suggest is the dsPIC. I don't think you need a dsPIC, FPGA combination since Audio processing is not heavy. So I think you better start with a dsPIC such as 30F4011 and when you think it needs some more power, then we could introduce a co-processor or FPGA to minimise the load on the main uC. But I'm sure if you write optimal codes, this will not be required.
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Re: DSPs Vs. FPGAs Vs. Microcontrollers for uni project

Post by Yurihalo » Mon Mar 26, 2012 9:28 am

Thank you very much for your reply.... so since you have mentioned about a backup co processor/ fpga, i did some search and found some options as follows:-

http://www.opalkelly.com/products/xem3001/ from Xilinx
fpga used is a xc3s400 8064 Logic elements. 1 logic cells = 4-input Look-Up Table (LUT) plus a ‘D’ flip-flop


http://www.altera.com/education/univ/ma ... board.html from Altera....
fpga used is a EP4CE22 with 22320 logic elements

A four-input look-up table (LUT), which can implement any function of four
variables
¡ A programmable register
¡ A carry chain connection
¡ A register chain connection
¡ The ability to drive the following interconnects:
¡ Local
¡ Row
¡ Column
¡ Register chain
¡ Direct link
¡ Register packing support
¡ Register feedback support

i really am inclined to use the DE0 nano which comes at an academic pricing of $59 commercial pricing of $79 while the xilinx model is at $179...

so based on your experience would you recommend the altera or xilinx option (i've worked with altera prviously so i am slightly biased towards altera but i really would like to know whther my selection is okay)?

p.s:- you are so lucky to have worked with DSP's and FPGA's.....
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Re: DSPs Vs. FPGAs Vs. Microcontrollers for uni project

Post by TRONICLK » Mon Mar 26, 2012 2:44 pm

Xilinx Vs. Altera ;)
It's like we compare Merc with BMW. Merc has the name for quality still BMW has the same features for a less price.
Same story with Ti Vs. Analog Devices and Atmel Vs. Microchip.
All these companies manufacture very good quality chips but there is something called brand name which is very strong in sales and marketing.
As users, I think what we will have to consider is to choose the cheapest chip that suit our requirement marginally. More clock speed, more peripherals means more price.

I'm not honestly pushing you on using what we have in our stock. Our stock is for our products. We do component sourcing and EVMs to cover the hole here. As you know it is not easy to earn with those in Sri Lanka. Our market is still not wide enough for that. So I still would like to suggest you the dsPIC since it is easy to program your application with C than VHDL or Verilog. We never though dsPIC is giving such performance until we tried it out our selves. With it's floating point ALU, it gives unbelievable performance over any fixed point uC.

In a university project, I think it is better to concentrate on showing the results rather than demonstrating the technology availability. In some universities, they reduce marks for working on EVMs. They need their students start from designing circuit, making the PCB, do soldering, etc... I think those are must for an electronics engineer. An engineer who can't solder is useless. So have a good plan on your requirement, make a block diagram and then think which will suit your requirement marginally.

If you still want to go with FPGA, I had a quick look on Altera EVMs. DE1 looks very good for you since it has audio ports built in. They must be providing codes for reading samples, etc... so it will cut off 80% of your coding effort.
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Re: DSPs Vs. FPGAs Vs. Microcontrollers for uni project

Post by Yurihalo » Sat Apr 21, 2012 7:18 pm

Thank You very much for your reply...!!! I have this one final question....browsing through other forums i saw in one particular forum that DSP's use external flash memory , so would it be possible to actually issue commands to an Analog or TI DSP using a dsPIC(since it is faster and more reliable...)??
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Re: DSPs Vs. FPGAs Vs. Microcontrollers for uni project

Post by Yurihalo » Sat Apr 21, 2012 7:25 pm

http://www.danvillesignal.com/analog-de ... ammer.html ...sorry its not a forum but it is a website advertising a flash programmer
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Re: DSPs Vs. FPGAs Vs. Microcontrollers for uni project

Post by TRONICLK » Sun Apr 22, 2012 2:10 pm

browsing through other forums i saw in one particular forum that DSP's use external flash memory , so would it be possible to actually issue commands to an Analog or TI DSP using a dsPIC(since it is faster and more reliable...)??
External flash can be attached to even microcontrollers. If the internal flash is too small for the program, it is possible to use an external flash chip. However this needs more effort. On DSPs, in most of the cases, there will be a fair amount of internal flash memory.
I think you mean whether it is possible to have intercommunication between dsPIC and DSPs ? Yes, this is obviously possible. You can connect the chips through I2C like buses. However when there is a DSP, I'm sure there will not be any requirement for a dsPIC. Who wants to command a Ferrari using a bullock cart ;)
http://www.danvillesignal.com/analog-de ... ammer.html ...sorry its not a forum but it is a website advertising a flash programmer
As few guys explained here, DSP development needs lot of investment. This is where almost all of us get struck at the moment. For few industrial projects where we needs speed, accuracy and efficiency, we used DSPs. However since most of those were BGA which made it difficult to solder here, even with facilities to make PCBs for SMT components with quick prototyping milling methods (I think we are the only people in Sri Lanka who can produce a PCB prototype board within 30 minutes ;) ) we had import development kits and fixed them straightaway by only writing the firmware. For 1 or 2 boards, it is a complete loss to place a PCB order with BGA components.
So this is the reason for us to recommend dsPIC to enthusiasts in Sri Lanka. When you are familiar with dsPIC, I'm sure it is a simple job to move to DSPs.
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