The XCore rev. of the USB 2.0 Audio card

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lilltroll
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The XCore rev. of the USB 2.0 Audio card

Post by lilltroll »

I have been using the USB 2.0 Audio card for about a ½ year now, and there are also several others here that have the card.

I have several ideas of HW-layout changes for the card, and since the design files can be downloaded I would like to collect different ideas from the existing users what they would like to be improved in a future rev. of the card.

I will edit this post and paste all good ideas below:
Personally I like the low-latency anti-alias filters, making it possible to use it for DSP. So I prefer to stick to Cirrus converters.

If this turns out good I might make 10-20 prototype PCB boards (in total) and send it away for free evaluation to people here that are helping me to make it happen. (I mean it´s almost free to make extra cards, so I can give them away for free, if you help me to find things that needs to be improved). On the other hand, I will be the one that makes the final decision what to change and what to keep as it is.

List of changes:
Change the analog ground to the CODEC
Add support for 5V external power supply in stand alone mode.
Use buffered inputs with overvoltage protection, and buffered outputs supporting 32 ohms headphones (TPA152).
Change the CODEC to a one with included PGA an mic BIAS (CS4245 or CS4265).
Run the CODEC as a slave in I2C mode, including controllability over MDIV1 & MDIV2.
Add Xlink support (if possible)
Skip the multi clock layout - use Frequency Synthesis instead fed from the USB clock (CS2300)
Change to L2 chip to add much more free MIPS, if it doesnt make the PCB too complex - othervise use 2 L1-64.
Have the possibility to stack several stereo cards to add more channels. Of course not the way to do it in mass production - but good for testing.


Probably not the most confused programmer anymore on the XCORE forum.
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lilltroll
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Post by lilltroll »

I started to ECAD a solution that will fullfill all the wishes.
At the moment my plan is to make a module for the Amino card.
That way I get both USB and Ethernet and 2 L1's.
I will also try to make it possible to stack 2 soundcards on 1 Amino to get more channels.
CODEC.jpg
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CODEC.jpg
CODEC.jpg (47.37 KiB) Viewed 4172 times
Probably not the most confused programmer anymore on the XCORE forum.
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Folknology
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Post by Folknology »

Right I have had a look at Amino-Alpha routing and think I can get the 13Mhz clock down on to the aux pins in between "B" and "D". That way you can take all the connections you need from one connector to the south. I will probably use a right angled 32pin female connector pointing south for this purpose see image.

This provides a couple of advantages:
1) Frees up the area for a separate concurrent shield on top
2) Works better for expansion cards that have a number of connectors

On a southward horizontal expansion you have 3 free edges for connectors, compared to shields which have pins in the way. You could also probably fit more channels into a single card with connectors.

let me know your thoughts, is this a better option?
Attachments
south-exit.png
Image show southward right angled 32pin connector
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Image show southward right angled 32pin connector
Image show southward right angled 32pin connector
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lilltroll
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Post by lilltroll »

It's imperative to make a good solutions for the interconnection.

Do you mean something similar to this PCI-104 board

Image

Microchip started to use a compact type of surface mount connector.
Image

Will you be able to stack several boards ?
Probably not the most confused programmer anymore on the XCORE forum.
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Folknology
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Post by Folknology »

The example I provided is based on a 0.1" right angled 2 x 16 female on the south of the board. It carries all of the digital signals you require I think. This enables a board to be connected horizontally rather than on top like a shield. That gives you more free edges on your board for connectors, if you can benefit from that.

regards
Al
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Folknology
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Post by Folknology »

If We use a straight female header (for the dual XPorts) and use extended pins on the shield it will be possible to stack them. if we use right angled connectors the stacking is left to the peripheral itself. Each peripheral also has to identify itself (if it doesn't it operates in a more limited mode.I am trying to find the best compromise for both identifying and multiplexing when stacked. I would imagine the following sequence of events:

1) XPort Peripheral is queried using XDA/XCK
2) Peripheral responds with identity and class
3) Management layer loads the HSM
4) Peripheral does its stuff until HSH finalised and unloaded.
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