[sdiy] DSP synth applications (was DIY Polysynths)

[thx1138]

On 7/29/09 1:24 PM, "Tom Wiltshire" <tom at electricdruid.net> wrote:

> If it helps, I second what Eric said.
> 
> Obviously different people have different wish-lists, but the SPI is
> a must. If you've got that, you can sort out the lack of ADC yourself.
> Like Eric, I can see a lot of uses for a reasonably powerful 24-bit
> DSP which doesn't require a huge amount of support circuitry to get
> it running.
> 
> I've recently been looking at the Spin FV-1 and the Alesis/Wavefront
> AL3101/3102. Both of these chips have their uses, but neither of them
> can do what I'd like them to do. I suspect the Soundbite DSP 56371
> actually can, but it's a bit of a hurdle to find out for sure.
> 
> Thanks,
> T.
> 
> On 29 Jul 2009, at 19:58, Eric Brombaugh wrote:
>> Terry,
>> 
>> First, thanks to you and your colleagues at Freescale for making
>> the SoundBite boards available. I picked one up early last year and
>> got as far as writing a few simple test apps. I worked a bit with
>> David DiCarlo on reviewing some of the documentation and debugging
>> some IDE conflicts with ARM/OCD tools installed under WinXP.
>> 
>> The DSP56371 used on the Soundbite looks like a potentially useful
>> part for a number of synth applications I'm familiar with. That
>> said, the lack of standard interface peripherals is a significant
>> hurdle. Anyone wishing to do more than rudimentary digital bit-
>> banging for user-interfaces is probably going to have to add a
>> second, more general-purpose MCU to handle things like MIDI, CVs
>> and user interfaces. Not that this is an onerous problem, but it
>> does create barriers that will discourage a significant fraction of
>> the potential user base.
>> 
>> Most of my audio DSP experience has been at the lower end of the
>> performance spectrum - things with 20-60 MIPS and 16-bit wordsizes.
>> I've become pretty familiar with the compromises that these
>> restrictions impose and I'd love to see some inexpensive parts that
>> are easy to use in a DIY context and provide more horsepower and
>> resolution. My wish list looks like this:
>> 
>> * >= 24-bit words
>> * >= 60MIPS
>> * >= true DSP with MACs and multi-bus operand prefetches/addressing
>> * fast vectored interrupts from on-chip sources
>> * single-cycle (no wait) on-chip memory accesses (program & data)
>> * >= 16kword on-chip data SRAM
>> * >= 32kwords program flash (or SRAM auto-loaded )
>> * At least one I2S-capable interface
>> * SPI, both master and slave capable
>> * UART
>> * >= 8 GPIO
>> * >= 3 32-bit timers
>> * >= 4 channels 12-bit ADC
>> * <= 144-pin TQFP (48, 64, 80 preferred)
>> * < $10/ea in small qty from a common distributor
>> * free / low-cost development tools
>> 
>> It's a bit of a list, but several of the DSP56k parts already meet
>> many of the bullets. I believe that the biggest hole is with the
>> SPI master, UART and ADC (and the ADC would be less important with
>> several SPI master channels) - adding these capabilities would make
>> the 56k family quite attractive for my future projects.
>> 
>> Eric
> 
> 
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Hi Eric and Tom,

At this point I am collecting ideas and trying to see what my personal
finances will fund.

Paul and Csaba have been great to work with and have been poking around
platforms a bit.

I sent over some AR11, DSP Dev tools and Tone Core Pedal DDK for them to
experiment with.

I hope to find a few more "Gems" in the Linux area to help out on
applications development on our i.MX31Lite or i.MX platforms in general.

Your inputs are welcome to me as I need to see what the Synth DIY folks are
capable of.

Several folks just throw up their hands as it is too complex or expensive.
Some want more feature brought out, which is good feedback as we can always
build 2 sided boards cheaply.

ARM requires 6 to 10 layers of PCB and Ball Grid packages are more expensive
to layout and debug. Still I think I have some solutions there as well as we
will introduce some ARM 9 parts in TQFP in August.

This will make it easier to have ARM, LINUX and DSP platforms co-exist.

If you guys wish to correspond privately email me @ thx1138 at earthlink.net

Best regards,

Terry