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Old 20th September 2011, 08:58 AM   #31
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The aim is really to put together a box of DSP elements (digital bricks if you like) so that DIYers who have little or no experience of DSP can get started in building digital systems by picking the relevant components. That is active systems which are digital all the way up to the final power amp sections. Think of it as rather like a digital audio toolkit, 'Arduino' for audio tweakers.
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Old 24th September 2011, 01:21 AM   #32
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STM just announced their new range of ARM Cortex M4 chips - here's a link to a dev board which might whet somebody's appetite. Looks like a real bargain at $20 (hat tip jkeny for the link):

STM32 F4 series of high-performance MCUs with DSP and FPU instructions | Dangerous Prototypes
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Old 26th September 2011, 10:19 AM   #33
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Quote:
Originally Posted by abraxalito View Post
The aim is really to put together a box of DSP elements (digital bricks if you like) so that DIYers who have little or no experience of DSP can get started in building digital systems by picking the relevant components ... Think of it as rather like a digital audio toolkit, 'Arduino' for audio tweakers.
Something like DSP Concepts AudioWeaver ? ARM Cortex-M4 demo from DSP Concepts - YouTube
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Old 26th September 2011, 04:09 PM   #34
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Nice idea
Is it possible to reach open source control/programming for TAS3108?
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Old 27th September 2011, 12:50 PM   #35
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Something like DSP Concepts AudioWeaver ?
Not really what I had in mind because its quite unclear from that short video whether what's shown there can work untethered from the PC. He clicks some objects and that goes over USB to the development board, but how does that all work when there's just a standalone piece of hardware? I'm much more interested in creating some self-contained kit.

Incidentally while we're on the subject of Cortex M4 (one of my favourite subjects ) TI has recently extended its range of Stellaris MCUs into M4 land. Here's a link if anyone's curious - seems they're lower-end devices than those from NXP and STM which makes them nice and complementary. There's no word yet on availability and the dev board is no bargain at $149.

LM4F110 Series | Stellaris® ARM® Cortex?-M4-based Microcontrollers | TI.com

The big plus that I can see for these parts from the audio perspective is they all have 4 (yeah, count 'em) SSPs. These ports can be pressed into service as I2S. There are no native I2S peripherals though. Whilst they're relative sluggards at a paltry 80MHz they are claiming some pretty impressively low power specs.

@boggy - Can't see much possibility in open source for a TI-proprietary chip with their own proprietary support toolset. Its the one Bruno's using in his UcD modules isn't it? Fairly good bang for the buck but very limited future prospects being only a single source.
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Old 7th October 2011, 04:46 PM   #36
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Interesting blog post which provides a bit of perspective and background as to why I'm so keen on Open Source DSP using ARM on a standalone hardware platform - as opposed to doing everything on a PC. The writer's as bullish as I am on Open Source hardware :

Why the Best Days of Open Hardware are Yet to Come bunnie's blog
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Old 14th October 2011, 08:52 PM   #37
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For abraxalito: How do you convert spice simulation to dsp code? I think you have some platform in your mind. Can you educate me how you turn it to actual product?
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Old 14th October 2011, 10:49 PM   #38
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Originally Posted by abraxalito View Post
Not really what I had in mind because its quite unclear from that short video whether what's shown there can work untethered from the PC. He clicks some objects and that goes over USB to the development board, but how does that all work when there's just a standalone piece of hardware? I'm much more interested in creating some self-contained kit.
Why not use a Smartphone or a Tablet for configuring an inexpensive, low power, barebone DSP blackbox the size a cigarette packet ?

The Smartphone or the Tablet could emulate a DCX2496 panel.

The Smartphone or the Tablet could display a block diagram. Clicking on a block, you could enter new parameters.

The Tablet could display a workspace allowing you to drag and drop elements from a library (adders, substractors, delays, IIRs, FIRs, level control, limiter) for creating your own block diagram.

You would be able to save your own settings and designs, not only on the DSP blackbox, but also on the cloud. This way, you could publish your design and make them available to others. Complex optimizations and measurement sessions could execute on the cloud. Extensive databases containing speaker data and related stuff would be accessible through the cloud.

It all depends the software running on the Smartphone or Tablet. The Smartphone or Tablet would load, connect and configure DSP blocks as code segments into the DSP box. Even if those blocks don't show on the GUI (like in the DCX2496 emulation). This way, all three different GUI approaches decribed above can interact with one common DSP software running into the DSP blackbox.

What is needed inside the DSP blackbox is a PCB containing a decent CPU equipped with Bluetooth, four I2S lanes, one SPI lane, and some expansion connector. The expansion connector is there, for hooking one S/PDIF (or Optical) receiver, one stereo ADC, up to four stereo DACs, and one Asynchronous Sample Rate Converter (ASRC) if needed.

The Freescale Symphony Soundbite Development board (DSP56K family) seems appropriate, provided we can hook a Bluetooth module on the SCI. I guess it is now possible to write the DSP software in C, however the C compiler & debugger may not be "open and free".

The ADI SigmaDSP platform may beat the DSP56K platform if using the increased resolution, and may lead to a more compact PCB because of having DACs on board (what about their quality ?). Is there an "open and free" C compiler & debugger available ?

An ARM Cortex-M4 seems less appropriate, as currently there is no M4 chip equipped with four I2S. How to persuade an M4 to output four I2S lanes, without a FPGA or without a PLD in order to remain low power and low cost ? But on the other hand, surely there are "open and free" C compilers & debuggers available.

Microchip PIC32 MX5/6/7 have four SPI, but can they all operate as I2S ? Same issue as the ARM Cortex-M4.

What would you advise ?

Regards,
Steph

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Old 14th October 2011, 11:44 PM   #39
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How do you convert spice simulation to dsp code? I think you have some platform in your mind. Can you educate me how you turn it to actual product?
I'm happy to share the assembly source code for what I've so far written. That's an FIR filter implementing that LTSpice simulation (11 tap FIR) running on an LPC1113 (which is a Cortex M0). The LPC1113 system takes in I2S from a QA550 wav player and puts out I2S to my experimental DAC. Would that help you? I'm not sure about the level of detail you'd like or your hardware/firmware experience which is why I ask.
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Old 14th October 2011, 11:59 PM   #40
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Quote:
Originally Posted by steph_tsf View Post
Why not use a Smartphone or a Tablet for configuring an inexpensive, low power, barebone DSP blackbox the size a cigarette packet ?
Now you're talkin' A low cost, low power, low-EMI open source crossover box is one of the things I'd like to work towards yep.

Quote:
The Tablet could display a workspace allowing you to drag and drop elements from a library (adders, substractors, delays, IIRs, FIRs, level control, limiter) for creating your own block diagram.

You would be able to save your own settings and designs, not only on the DSP blackbox, but also on the cloud. This way, you could publish your design and make them available to others. Complex optimizations and measurement sessions could execute on the cloud. Extensive databases containing speaker data and related stuff would be accessible through the cloud.
Is that kind of software writing something you're comfortable with? Having the user interface on a tablet while the crunching goes on on dedicated hardware is the notion that appeals most to me. Creating a social network around DSP also is very attractive - Facebook for audio-DSP geeks

Quote:
An ARM Cortex-M4 seems less appropriate, as currently there is no M4 chip equipped with four I2S. How to persuade an M4 to output four I2S lanes, without a FPGA or without a PLD in order to remain low power and low cost ? But on the other hand, surely there are "open and free" C compilers & debuggers available.
Some of the M4 boards from STM are currently winging their way to me, so this is something I'm going to be looking at in the near future. Stay tuned

Quote:
What would you advise ?
I'm sure you can guess the answer I'm giving! Have your M4 STM 'Discovery' boards arrived yet? I see Mouser's sold out of the first batch. Price has come down from the original $20, now $16. Mine were ordered when they were $15.
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