microprocessor advice needed

Hi everybody, i'm in need of some expert advice. I'm planning an audio spectrometer project whereby i need to sample an audio signal, perform the fft algorithm and then display the results on some form of graphical display (I'm thinking along the lines of an OLED). The FFT i'm going to do is only 128 points so memory requirements aren't that intense. Naturally, i would like the whole process from sampling through to display to be as quick as possible, but it doesn't have to be real time, just quick enough to reflect the music without any noticeable delays

My question is what is the best microprecessor to use for implementation. I believe a DSP processor would be the best for the FFT but probably wouldn't suit the rest of my needs, right? I'v also heard about the DSpic range but really don't know much about these and also don't have that much experience in PIC programming. Ideally i would like to use some form of AVR Atmel, but would any of these microcontroller's be adequate for my project?

Any advice is much welcomed and greatly appreciated.
Regards

Just look at ARM Cortex M4 core. Up to 200 MIPS. It is more then enough.
But there is another way. Use external pass-band filter with channel selection. I will try to find the correct chip name if you interesting. This chip is using in equalizer displays.

It it's AVR you after take a look at the EVK1104 from Atmel. It uses a 32UC3A256 Micro and has a neat demo of FFT on 2-input signals. The 32-bit UC3 has a very good DSP library for carrying out the FFT itself. Using it for sampling music shouldn't be a big stretch. If you download AVR Studio 5 you can take a look at the sample code for the UC3_DSPLIB_DEMO.

I will try to get a good sample picture of the output display up here for you to see.

[UPDATED]


Shown in the rightmost window is the FFT of the 2 input signals.

You could use the input section of the circuit below to process you audio signal before inputting to Analog-to-Digital pin of the chip.

https://www.olimex.com/dev/images/msp430-169stk-sch.gif

This project is something I would be really interested in doing myself for fun so if you need any assistance let me know.

Hey easyrider please do get that chip name, I do want to look more into that option.

Thanks joey, that development board does seem perfect, the only issue is that its a university project so budget becomes a bit of a problem and they don't like us using development boards that much, we're pushed to do as much of the hardware as possible ourselves. I've also seen a few fft projects where just an 8-bit processor was used, do you think i could do this too, as using the 32-bit micro's seems a little daunting for someone with as little experience as me. If you really are interested, i'd probably be needing a lot of assistance along the way so i'll definitely keep in touch.

Also can anyone give me further insight into the DSPic's and whether i should be looking into those over the AVR's?

I think dsPIC33 series would be a good choice. They have DSP functionalities like X and Y memory mode, hardware mac instructions, hardware barrel counter etc. They run at up to 40 MIPS which id more than enough for performing FFT of audio signal. You also get free DSP library from Microchip.

I understand. 32-bit micro is a bit daunting for me also and I've a lot of 8-bit experience. The 'heavy lifting'' though is done for you with the ASF ( AVR Software Framework) but there would be quite a bit of a learning curve. If the EVK is a bit of overkill the full schematic is available here:

http://www.atmel.com/dyn/resources/prod_documents/EVK1104_Schematics_BOM.zip

You could take the usefully parts and duplicate for your own PCB. You could use one of the UC3 devices with a much lower pin count also.

If you really want an 8-bit AVR solution there should be a lot of suitable projects already out there. One good one is here:

AVR FFT code // Adrian Lombard

It outputs results over RS232 but you could modify to use some sort of display.

This is a link for schematic that I promised - simple spectrum analyzer.
ÐàäèîÊîò :: Ñïåêòðîàíàëèçàòîð çâóêà ÏÈ×ÎÊ.
It is on russian. If you will have any troubles with translate, let me know, I'll help you.

Just found this thread from 5 years ago:

https://www.edaboard.com/threads/58034/#post259987

It was started by me.....I still haven't got around to building one. Hope the link helps, looks like a good one.