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DSP chip ??

Started by phil123456 3 months ago27 replieslatest reply 2 months ago171 views

Hello,

I struggle to find a hand solderable (soic ? msop ?) DSP programmable chip

I tried a teensy and a raspberry pi to DSP some simple audio to make audio effects based on FFT/iFFT

back in the day there were dedicated chips and (embeded & small) boards, but it's so hard to find nowadays

thanks for the time you'll spend on this one

Phil


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Reply by Tim WescottJuly 1, 2020
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Reply by DaniloDaraJuly 1, 2020

What about DSPic from Microchip?

There are several versions easy to solder.

You can eve find some DIP Cus

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Reply by phil123456July 1, 2020
thanks mate, I'll have a look
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Reply by phil123456July 1, 2020

I cant really find any info about this

more like general farnel dev boards and stuffs

any chip in particular ? tutorials ? recommendations ?

thanks

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Reply by sami_aldalahmahJuly 2, 2020

It is interesting how things changed in the DSP industry. Nowadays most DSP features exists in MCUs as engines and software libraries. 

Have a look at the ARM-based board STM nucleo board. It has the DSP capabilities and a large user base and support.


https://www.st.com/en/evaluation-tools/stm32-nucleo-boards.html

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Reply by phil123456July 2, 2020
thanks I'll have a look, the site is not really handy when it's about checking the dimensions or price of the board
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Reply by sami_aldalahmahJuly 2, 2020

You can check the board price on digikey or sparkfun. However this board in particular is very cheap, it’s around $15. 

https://www.digikey.com/product-detail/en/stmicroelectronics/NUCLEO-F446RE/497-15882-ND/5347712

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Reply by phil123456July 2, 2020
ok but it's everything but a RPI Zero/teensy form factor :-)
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Reply by sami_aldalahmahJuly 2, 2020

Maybe it looks big in the pictures but it’s almost the same size as the RP. If you’re for a smaller size google the stm32 blue pill but make sure it has the floating point processor unit (FPU). 

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Reply by phil123456July 2, 2020

rp zero is 2.5cm wide

teensy, is like 1.5cm wide

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Reply by dszaboJuly 11, 2020

Nucleo32 is a hair under 1.9cm. The L4s are nice little chips.  Never tried to do spectral processing with them, but gut feel is it would be doable.


or this dude is pretty new but looks mean for the size: https://www.digikey.com/products/en?WT.z_cid=sp_497_0928_buynow&Enterprise=44〈=en&Vendor=497&mpart=NUCLEO-G431KB

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Reply by jbrowerJuly 2, 2020

Phil-

At first I was going to suggest you use an older DSP, but it would have to much older, 15 years, maybe closer to 20.

Another idea is to choose a small, modern DSP you like, then look for an SMD to pin adapter, you can search for "SMD adapters".  There are lots of providers, normally these are used for test/debug purposes. It might not look good, but could be quite functional, especially if you avoid using a DSP that requires external DRAMs and other high speed connections.

-Jeff

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Reply by phil123456July 2, 2020
yeah I do that all the time, I just don't know what chip to choose
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Reply by jbrowerJuly 2, 2020

Phil-

Hmm, in that case maybe look at TI's fixed-point C5416 or C5510. These came out in 2000-2006 time-frame, but TI still shows them as "Active". Note the 5416 has a LQFP-144 package -- not exactly easy to solder, but do-able.

Both are very small. This page has some pics showing just how small:

https://signalogic.com/sigc54x

What size FFTs do you need to do ?

-Jeff

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Reply by phil123456July 3, 2020

it depends, 64 to 4096, but are there no more recent chips ?

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Reply by jbrowerJuly 3, 2020

Phil-

Maybe have a look at the ADI "SigmaDSP" line:

https://www.analog.com/en/about-adi/news-room/press-releases/2017/5-23-2017-analog-devices-next-generation-dsp-for-automotive-audio-applications.html

These were released in 2017. They come in an LFCSP package, which believe it or not looks hand solderable (if you're skillful).

-Jeff

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Reply by phil123456July 3, 2020

thanks I'll check this out, mate

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Reply by jbrowerJuly 3, 2020

Phil-

Even better, how to connect SigmaDSP devices to Raspberry Pi via I2S:

https://ez.analog.com/dsp/sigmadsp/f/q-a/65427/con...

You can't miss, hehe.

-Jeff

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Reply by phil123456July 3, 2020

sheers mate, I'll definetely have a look at this

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Reply by PhilHawJuly 15, 2020

The FV-1 from Spin Semiconductor might work for you. It's used in many guitar effects pedals, amps and mixers. It's particularly well-suited to reverb and delay effects. It's a 28 pin SOIC and even I can solder it (I'm 68 next week and only have one good eye and a n illuminated magnifier!).

In the US it's distributed by Experimental Noize and in Europe its available from Profusion in the UK.

Experimental Noize

Profusion UK


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Reply by phil123456July 15, 2020
sounds cool but I dont see the instruction set in teh datasheet

http://www.experimentalnoize.com/manuals/FV-1.pdf


also checked the application notes, it does not talk about any FFT/iFFT :-(

http://www.spinsemi.com/programs.php

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Reply by PhilHawJuly 15, 2020

The instruction set link is further down the page. http://www.spinsemi.com/Products/datasheets/spn1001-dev/SPINAsmUserManual.pdf


Sorry, I missed your original reference to FFT/iFFT. AFAIK There are no specific instructions for those. As a DSP noob I thought you could code an FFT using the basic instructions?

Also take a look at the newer FXCore chip from Experimental Noize as it is probably more powerful but it does require external CODECs which the FV-1 has built-in.

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Reply by phil123456July 15, 2020
with 128 core instructions per sample clock, it's gonna be short to do FFT

also no examples to do so, DSP without dedicated FFT/iFFT instructions is gonna be challenging

I am pretty sure I already have samples of these ship, I had them a while ago when the company was called wavefront or something


thanks anyway

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Reply by PhilHawJuly 15, 2020

OK I guess it's not going to do what you want but it is amazing how much you can squeeze out of those 128 instructions, albeit not a FFT!

The chip was the design of the late Keith Barr who founded Alesis and MXR before setting up Spin SemiConductor to manufacture the FV-1.

Did you say you had considered the Teensy? I know it's a module not a chip but it's very small and powerful and well-supported with audio libraries. There is also an Audio System Design Tool (drag and drop) which includes a couple of FFT modules. I grabbed a snippet of the screen and there's more details here

annotation 2020-07-15 195417_20356.png

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Reply by phil123456July 15, 2020
no I actually come from the teensy 3.6

hence this thread

indeed there is a nice audio designer, which makes it silly the ADC's are not up to the level of the rest of the board/software...the ADC on the teensy are horsesh!t (50% SNR)

teensy 4.0 is more recent but has the same issue AFAIK

they suggested to hook up an I2S breakout board, but I was not lucky doing so, I get audio cracks cos the clock is jittering (20Mhz) and I got fed up with it

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Reply by PhilHawJuly 15, 2020

LOL Yes, agreed the ADCs are indeed what you say though I don't think mine was as bad as 50% SNR!

Best of luck finding something suitable,


Phil.

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Reply by phil123456July 15, 2020

I built a whole device around the teensy

even made a .NET app communicating with it through usb to display the different stages of the signal processing

can't tell you how disgusted I was

well thanks for the help in any case...

Phil