Multi Channel Audio Mixer daughter board project

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glenn
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Multi Channel Audio Mixer daughter board project

Postby glenn » Wed Apr 12, 2017 5:54 am

Multi Channel Audio Mixer daughter board project

Hello Everyone,
I am currently researching for a multi channel audio mixer project and I found XMOS to be the best solution for this project. I saw the startKIT and it seems best for my application simply because its cheap. :)
If this project become successful, I may release it as an open source project on my site [url]tataylino.com[/url]. I am used to arduino and PIC mcu so this XMOS is new to me.
I am aware of the slice board with 4 inputs and outputs but I want to make my own because I want to have at least 8 inputs and maybe 4 or 6 outputs.

Since I am new to XMOS, I am not sure if the startKIT is suitable for my requirements so I need your advice.

Here are my requirements:
* at least 8 audio inputs
* at least 4 audio outputs
* Each mono audio channel input have Gain, Volume, EQ, and simple Compressor controls
* Mix all inputs
* Volume and EQ controls on each outputs
* USB streaming on each inputs
* Record each track on a SD card or USB flash
* Controls may be on a tablet via wifi

I have a doubt that these are too much for the startKIT to process but as I've said I am new to XMOS mcu so I may be wrong. Please advice if its possible or if not, please tell me what can be done.

Thanks in advance!

PS: The multichannel development board is too expensive for me so I decided to make my own extension board for the startkit. My goal is to have a cheap extension board product for the startkit. This product is for those who can't afford the digital audio mixer and/or multi channel audio interface and want to build their own audio mixer/interface.
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Bianco
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Postby Bianco » Wed Apr 12, 2017 11:04 am

The startkit does not have a user-programmable USB interface, the USB interface on the chip is already used by the onboard debugger.
Rics
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Postby Rics » Wed Apr 12, 2017 11:36 am

Hello everyone, i'm a newbie of the platform and got, more or less, the same needs of Glenn (although a bit different on the features), so i'm following this thread.

Getting what Bianco wrote, to make something like Glenn listed, i think that an XK-SK-U16-ST USB Slice Kit at least is needed then. Correct?
glenn
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Postby glenn » Thu Apr 13, 2017 1:22 am

Would it be possible to reprogram the board via jtag to use the tile0 for user? I believe the tile0 is dedicated to usb and debugging.
mhelin
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Postby mhelin » Sun Apr 23, 2017 7:57 pm

You have to first build regular Startkit project for the I2S mixer part. You have limited usability for the USB part though. This means you implement the USB audio stack on debugging tile but can only load the USB firmware dynamically. You have to route the data from the Dark Side to the user tile using either the XMOS links (can't say how it could be done though I guess much like A/D access) or external pins on Startkit board. There are few pins which are routed from the chip to board. I have implemented USB DAC for Startkit, it was running standard XMOS USB audio stack, I just changed the pin definitions before compiling the code.

There is an example on dynamic loading on Github: https://github.com/xcore/proj_xtag2/tre ... dynamic_xe

There used to be a related application note on XMOS site, but is now removed.

Anyway, in all I think you can at least start your project on StartKIT, but maybe want to use some more powerful XMOS chip to finalize you product. There is an interesting project on Diystompboxes forum (http://www.diystompboxes.com/smfforum/i ... 114354.120) coming that will offer quite a powerful XMOS board for you purposes, please check that. It will contain an easy to use software framework for all your needs regardin audio DSP at least (the SD implementation provided by XMOS afaik needs some improments).

Wish you luck with your project, May the Force be with you!
Last edited by mhelin on Sun Apr 23, 2017 8:04 pm, edited 1 time in total.
mhelin
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Postby mhelin » Sun Apr 23, 2017 8:00 pm

Could anyone from XMOS tell from where to find this document (that the original URL, maybe it's moved to somewhere):

https://www.xmos.com/download/public/Dy ... -XTAG2.pdf
glenn
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Postby glenn » Mon Apr 24, 2017 10:14 am

Hi Mhelin,
Thanks for the very informative response. I am now thinking of just making my own development board to fully use the USB. One more question: Can you select any of the IO pins for the I2S? Or there are only select pins that can be used for I2S?
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johned
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Postby johned » Mon Apr 24, 2017 11:38 am

Hi Glenn,

For this project, I would use the xCORE-200 multichannel board as the basis : https://www.xmos.com/support/boards?product=18334
It has all the I/O you require and also the new higher performance xCORE-200 processor.
If you want to design your own board then you can start with the schematics on the above page.

All the best,
John
mhelin
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Postby mhelin » Mon Apr 24, 2017 6:32 pm

Designing own board is not that easy unless you are very professional and experienced designer (bot HW & SW). Also the largest pitch size is 0.5 mm pitch (in 64-TQFP package, single core XUF208 chips with upto 256kb RAM) which is really difficult to solder by hand.

However, regarding the StarKIT USB there is also the xSCOPE interface available which could easily stream your 8 audio channels to PC (as binary data, using your own protocol), see
https://www.xmos.com/support/appnotes?s ... 20examples
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johned
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Postby johned » Mon Apr 24, 2017 6:35 pm

Good comments mhelin.

I would caution that xSCOPE is lossy and there is no guarantee that the data will not be lost.

Best regards,
john

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