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USB DAC Project for HPA

Posted: Tue Jan 16, 2018 8:50 pm
by JPS64
Hello,

I´m just designing a Class A Headphone Amplifier (Amplifier ready) and I need now an USB Audio DAC (PCM and DSD).

The xCORE-AUDIO Hi-Res DAC/HPA Platform (with ESS DAC) is the ideal candidate but the Silicon XHRA-2HPA-TQ64 is obsolete.

Can I replace this one with another one without a lot of work. Of course, I´ll design a new PCB layout.

Thank you in advance,
JP

Re: USB DAC Project for HPA

Posted: Wed Jan 17, 2018 4:08 pm
by andrewxcav
This should be doable on just about any xcore 200 device. The easiest thing to do is pick one that has a reference design:

https://www.xmos.com/support/software/uac2

That dev board is really great for prototyping, but the actual silicon on it should be a widely available xcore 200 part.

Re: USB DAC Project for HPA

Posted: Wed Jan 17, 2018 4:23 pm
by infiniteimprobability
Can I replace this one with another one without a lot of work. Of course, I´ll design a new PCB layout.
Yes - in fact it should be possible to be pin compatible so no need for a new PCB.
This should be doable on just about any xcore 200 device
andrewxcav is right, although pick the XU208-128-QF48-C10 and it should be pin compatible.

We are talking internally at the moment about making an example project, based on https://www.xmos.com/support/software/uac2, that will get you most of the way there..

Re: USB DAC Project for HPA

Posted: Thu Jan 18, 2018 9:08 pm
by JPS64
Thank you for the answers.

I´m starting schematics and publishing for control.

JP

Re: USB DAC Project for HPA

Posted: Sat Jan 20, 2018 2:22 pm
by JPS64
Hello,

as promised, here the schematics.

Could someone do the mapping, table is in the schematics.

Should I use xSYS header, JTAG only or full xSYS header?

Regards,
JP

Re: USB DAC Project for HPA

Posted: Fri Jan 26, 2018 11:21 am
by infiniteimprobability

Re: USB DAC Project for HPA

Posted: Sun Jan 28, 2018 4:03 pm
by JPS64
Thank you!

I´m following your recommendation: anyway, I need an additional I2C interface to µC to be able to configure filters and to read mode and sample frequencies.

Here the first layout: I´m using MILL-MAX SLC Header during development.

JP

Re: USB DAC Project for HPA

Posted: Mon Jan 29, 2018 11:16 pm
by mon2
Correction - IF this design will be bus powered..(appears you are self powered using an external power source?)

Please add the inrush current protection onto the Vbus rail else you may face field failures. The latest datasheets for the processor offer one version of protection. There are other methods including the use of the USB load switch devices from Diodes Inc. (ie. AP2331) or similar.

Add a pull-up onto pin 4 (N9) of your reset supervisor. This pull-up may not need to be stuffed but place into your design as a CYA (cover your ....).

Wurth (L5) is a good company but expensive. Consider a review of the Taiyo Yuden inductors. Very cost effective and excellent quality.

https://www.xcore.com/viewtopic.php?t=5808

Perhaps consider to add some debug interface signals (XSYS interface) ?

Re: USB DAC Project for HPA

Posted: Wed Jan 31, 2018 11:19 am
by JPS64
Hi mon2,

thanks you for the comments: schematics attached.

Yes, correct, board is self powered and suggested XMOS inrush current protection added.

This board is mounted on testboard supplying Mill-Max springloads and external Glue (USB connector, RESET hold switch and so) for test and manufacturing (debugging using full xSYS-Header, flashing SPI FLASH): pull-up on RESET external.

When board functional so directly soldered on motherboard: powered with +5VDC, using I2S/DSD, I2C, logic to DAC; interfacing I2C to micro for GPIO (filter selection).

JP