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ODAC offerings from Various Vendors

Do you want an ODAC back panel for the O2?

  • yes for sure!

    Votes: 29 43.3%

  • I want to use the ODAC as stand alone unit.

    Votes: 21 31.3%

  • I'd rather wait for the ODA...

    Votes: 17 25.4%
  • Total voters
    67
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G

GeorgeBoudreau

Member
Joined 2010
It has been a year of so since I looked at the XMOS files. The big *if* is the license for their USB audio library.

One other issue with DIY is the actual assembly. I am pretty sure 99% (arbitrary number but close) of the builders cannot mount and inspect BGA or other odd mounting arrangement components. The XMOS L1 chip can be soldered but if memory serves me it could only process 2-channel stereo and not 5.1 or 7.1.

Another kicker with an open source project that reaches beyond 96k audio is licensing the driver. (not XMOS but the windows driver) Many years ago I talked to Centrance about licensing costs and was quoted $10k as an entry level. Don't know about you but I don't see me plunking down that amount of cash for a license and hoping the people will drop a few bucks in the bucket.

The big players amortize their costs across sales. Open source has no 'sales' to recoup costs from. Everyone chips in time and some resources and everyone benefits.

If the XMOS UAC1/2 code is NDA free and we can create a driver-less UAC1 version as a starting point I will gladly layout the boards. UAC2 is dependant on the driver and if Nikolay's ASIO driver (from the audio-widget group) will satisfy folks that may be a path for an open source XMOS design.
 
G

GeorgeBoudreau

Member
Joined 2010
I had a look at the XMOS site again. The Thesycon driver is available as part of the XMOS XS1-L01 when purchased in bulk. Bulk purchasing has its own headaches (250 min for the 48 pin version, 90 for the 128 pin).

I expect you can switch between UAC1 and UAC2 but have not looked into it.

If I have the time over the weekend I will see what I can dig up info wise and turn out a minimum design.. No bells, no whistles just a bare bones I2S design that can be expanded on.

George
 
F

fitzfish

Member
Joined 2010
qusp said:
yeah I dont get it, why use a 12Mhz clock when the majority of users will be playing 44.1khz material
Click to expand...
A reference clock is necessary at any USB target device for internal circuitry that recovers the clock from the USB host interface data (desktop, laptop, etc). This reference clock is also often used as the reference clock for an internal PLL that generates the audio master clock for its Audio interfaces.

It appears that the 9023 clock is driven from the pin 3 output on the 7022 in this case

Cheers,
Dave
 
G

GeorgeBoudreau

Member
Joined 2010
SY said:
:cop: By "reference schematic," do you mean the actual full schematic of the device being sold here?
Click to expand...

The reference schematic refers to the XMOS evaluation board.

I am hoping the group will be able to create a DIY USB->I2S board based on the XMOS cpu product. If XMOS is friendly with their audio library this may be possible. If they require restrictive licensing then a different processor will have to be looked at.

The end target is an open source ODAC with full schematics and firmware available.
 
G

GeorgeBoudreau

Member
Joined 2010
fitzfish said:
A reference clock is necessary at any USB target device for internal circuitry that recovers the clock from the USB host interface data (desktop, laptop, etc). This reference clock is also often used as the reference clock for an internal PLL that generates the audio master clock for its Audio interfaces.

It appears that the 9023 clock is driven from the pin 3 output on the 7022 in this case

Cheers,
Dave
Click to expand...

That is correct. The I2S signals are:
pin 1 L/R clock
pin 2 Data
pin 3 Master clock
pin 6 Bit clock
 
qusp

qusp

Member
Joined 2009
fitzfish said:
A reference clock is necessary at any USB target device for internal circuitry that recovers the clock from the USB host interface data (desktop, laptop, etc). This reference clock is also often used as the reference clock for an internal PLL that generates the audio master clock for its Audio interfaces.

It appears that the 9023 clock is driven from the pin 3 output on the 7022 in this case

Cheers,
Dave
Click to expand...

I realised that after thinking about it, but I wasnt aware it had to share. thats why I asked if it was because it was shared with the MCU etc. it doesnt have to be shared with the audio clocks does it? I realise many do this, but certainly not all. the same is done with many of the UAC2 designs IE. they have a 12Mhz XO thats used for usb data and for the MCU, but anything I would consider has its own audio clocks. I presume the USB clock is needed onboard so it can act as slave sometimes too, while still acting as i2s master as in the case of async where the device. PC side design is certainly not an area I know a whole lot about
 
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