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Old 4th October 2013, 09:58 PM   #471
rsdio is offline rsdio  United States
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Quote:
Originally Posted by gmarsh View Post
I'm banging out a C55x design right now at the day job. There's been a few times that I've contemplated flying to texas to key someone's car, mostly CCS and emulator issues, but so far so good. Nobody else even come close to what the C55x can do for power efficiency.
I don't want to get too far off-topic, but since this is "open source DSP" I think it's still mostly on-topic:
Anyone working on C5000 firmware who is also using Texas Instruments' open-source dspLib should check out my errata section in their Wiki
DSPLIB - Texas Instruments Wiki
During my development process, I found five bugs in the source. These Wiki entries describe the problems and give information useful for correcting the errors.
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Old 5th October 2013, 02:52 AM   #472
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Originally Posted by gmarsh View Post
In a 16-bit DSP with the usual "1.15" format, the value 0.5 is 0x4000 or 16384.

If you multiply 16384*16384 together with an integer multiplier, resulting in a 32-bit number, you get 268435456 or 0x10000000.

In "2.30" format, this corresponds to 0.25. Typically you'd shift the result 1 to the left to put yourself in 1.31 format (with the result being 0x20000000), and then to go back to 16-bit 1.15 format, just drop the low 16 bits to give you 0x2000 - which in the original 1.15 format, is 0.25.

Things get weirder when you include sign bits and such.
Yes I had a look at the SHARC programmers reference manual and there are indeed different variants of the multiply instruction depending on whether you are dealing with fracts or ints so you don't use the integer multiplier variant if you want to multiply two fracts in a single cycle multiplier. No doubt the Cortex M4 has similar instructions to deal with fracts or integers
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Old 5th October 2013, 04:10 AM   #473
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Originally Posted by rsdio View Post
I want to thank twest820 and gmarsh for their comments on various processors and their comparative abilities.
You're welcome.

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Originally Posted by abraxalito View Post
And another not quite as old saying that goes 'don't feed the trolls'.
Hmm, I wouldn't necessarily go that far, though the continuing confusion over instruction sets isn't something I've a new response to. Did remind me to check on what's been happening with NXP's acquisition of Code Red, the answer being LPCXpresso 6 released last week with the maximum program download doubling on the free version to 256k. LPCXpresso 6 includes an NGX_LPC4337-Xplorer example, so looks like an update to the LPC4330-Xplorer's coming. The LPC4337 also happens to be the only 4300 part with flash DigiKey and Mouser stock in LQFP.

Could end up being a convenient configuration of offerings despite being limited to utilizing a quarter of the flash. Email to sales@ngxtechnologies.com bounces due to misconfigured forwarding on their end so I've got nothing in regards to a date for availability.
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Old 22nd October 2013, 04:17 AM   #474
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NXP's latest LPC43XX offering has upped the core count to three - two M0s now: LPC4370FET256 :: NXP Semiconductors
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Old 22nd October 2013, 05:07 AM   #475
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M4F too, but only available in BGA. (Besides, it'll be a small miracle if I get my LPC4337 board done before the part's LQFP package moves from qualification to production. So it's not like I'm stuck on that. )

The LPC4330 Xplorer apparently underwent a silent morph to the LPC4337 Xplorer (ref here, here, and here). Based on my email exchanges with them NGX sales is unaware of this despite similar changes on the LPC1850 Xplorer.
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Old 22nd October 2013, 05:27 AM   #476
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Those guys from PHILIPS/NXP know what they do. The NXP LPC4370 looks like a seductive 32-bit audio DSP engine with high quality USB-audio connectivity (asynchronous 2496 USB-audio?) and Ethernet audio streaming.
- Cortex-M0 #1 for dealing with USB/Ethernet audio protocols without involving the Cortex-M4
- Cortex-M4 left unencumbered so can dedicate entirely to audio DSP - this enables reintroducing audio DSP architectures basing on one hardware interrupt per sample, with the full audio DSP routine being executed each time a new sample is coming in - audio latency is kept minimal
- Cortex-M0 #2 dedicated to SGPIO emulating four I2S lanes, connecting to audio ADCs and audio DACs (multichannel audio, up to 8 channels).

Is there a prototyping board available ?
I wish there is one embedding a WM8580/8581 multichannel Audio Codec, because in such combination MCLK gets locally generated by the Codec (high quality audio clock not involving the DSP engine), and because the WM8580/WM8581 is providing an SPDIF transceiver as bonus, that can help building modern PHILIPS DSS930, DSS940 and DSC950 incarnations.

Is there a patent on the trick Philips used in 1994 in the DSC/DSS for superimposing a low bitrate serial channel on the SPDIF datastream ? This was needed for conveying the listening volume setting. See the attached pictures.
Attached Images
File Type: jpg Philips DSC-950 EBU + DIG CONTROL Interface.jpg (134.6 KB, 173 views)
File Type: jpg Philips DSS-940 EBU + DIG CONTROL Interface.jpg (351.6 KB, 168 views)
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Old 22nd October 2013, 05:38 AM   #477
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Quote:
Originally Posted by twest820 View Post
The LPC4330 Xplorer apparently underwent a silent morph to the LPC4337 Xplorer (ref here, here, and here). Based on my email exchanges with them NGX sales is unaware of this despite similar changes on the LPC1850 Xplorer.
This looks frightening. I've just got a few Infineon XMC4500 Relax Lite Kit delivered from HITEX. That Cortex-M4 engine looks especially clean.
XMC4500 Relax Lite Kit
HITEX is now using the same concept as Embedded Artists: a built-in hardware programmer-debugger containing its own XMC4500, that you can separate from the XMC4500 target. All pins are brought out using standard pin headers. This motivates me for designing a "shield" dedicated to audio DSP, containing a multichannel Audio Codec. Possibly a PHILIPS DSC clone, and a PHILIPS DSS clone. Oh, I forget to tell : on the XMC4500, the (many) SPI ports feature a I2S modality.
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File Type: png XMC4500 Relax Lite Kit.png (69.8 KB, 164 views)

Last edited by steph_tsf; 22nd October 2013 at 05:55 AM.
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Old 23rd October 2013, 01:16 AM   #478
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Originally Posted by steph_tsf View Post
This looks frightening.
It's common to sell things without knowing what they are and use misleading marketing names. Though usually the naming is misleading in the other direction. And, looking back at the emails, they don't rule out NGX just never responding to my follow up questions to their poorly composed initial reply. Agree this isn't a particularly good customer experience but the hardware seems fine and NGX has the only 43xx eval board offerings available under USD 100.

The UDA1380 codec on the LPC4330, er, LPC4337 Xplorer's nothing special. But it's enough to verify one's I2S or USB in -> DSP -> I2S out code. SGPIO0 to 14 are exposed on the Xplorer headers. So an alternate codec or DAC can be strapped to it. Or, more minimally, one can verify one's DSP XO and SGPIO code wiggles the proper pins. I like the arrangement as it allows almost total toolchain and firmware verification before sending an LPC4337 PCB to fab.

I just have, oh, five or six other projects to finish up first.
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Old 23rd October 2013, 01:49 AM   #479
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Originally Posted by twest820 View Post
SGPIO 0 to 14 are exposed on the Xplorer headers. So an alternate codec or DAC can be strapped to it.
Well, I never succeeded setting up a proper development environment for the few Xplorer boards I have here. If somebody has a kind of framework from where I can start - how to configure the development environment - how to run a very basic USB-audio -> twin I2S output (4 channels), that would help a lot op people (including me). Starting from there, one can safely design a "digital audio shield" for the Xplorer, hosting a WM8580 or WM8581 Codec. Possibly, implementing a PHILIPS DSC clone, or a PHILIPS DSS clone, a few straps allowing to select the modality.

Last edited by steph_tsf; 23rd October 2013 at 01:52 AM.
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Old 23rd October 2013, 02:22 AM   #480
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Abraxalito linked the talks a few pages back but here it is more specifically: Brewster LaMacchia's I2S stereo filtering example. There's also an older 5.1 sample from Keil.
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