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RE: iPad and external DACs

62.143.40.17

In Reply to: RE: iPad and external DACs posted by soundchekk on August 17, 2012 at 01:57:52

A little progress.
I looked up the TI TAS 1020B datasheet.
Page 21. The EEPROM header got a field called MaxPower given in n * 2mA.
That's probably the relevant parameter in the firmware.

But that means 1 parameter = 1 hardcoded value.
You most probably wouldn't be able to handle bus and external power on the same device with this.
The manufacturer would have to choose the worst case scenario (bus power).
On a first glance it looks to me that the 1020B would support 2 scenarios only.
Bus PS only or External PS only. A combined scenario wouldn't be possible...
...except you'd fake that value. Though I doubt that any manufacturer would do/risk that.

Let see how Tenor and XMOS are doing.

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::: Squeezebox Touch Toolbox 3.0 and more ::: by soundcheck

Edits: 08/18/12 08/18/12

Follow Ups:

RE: iPad and external DACs - soundchekk 03:22:57 08/27/12 (0)
Hi

A brief update.

I've been in contact with the guy who is building the real well done WaveIO interface (You'll find it on DIY audio).

He confirmed that you can set that MaxPower parameter inside XMOS firmware.

He even did it... ...and it worked on the iPad.

The main challenge though remains - at least for now:

You can't just change that header parameter on the fly. That would be required to run USB power and external power from the same device.

Anyhow. He'll be offering an iPad compatible (no need for a USB-hub) version of his Wave-IO device.

Cheers

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::: Squeezebox Touch Toolbox 3.0 and more ::: by soundcheck

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