Different Channel Count with different sampling frequency Topic is solved

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dkybchoi
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Different Channel Count with different sampling frequency

Postby dkybchoi » Fri May 12, 2017 9:52 am

Hi ,

As I know in a bigger Audio Interface product, it is possible to change the channel count on the fly when we select different sampling frequency from PC ( Host)

For example :
At the sampling frequency 48KHz , the system can support 18 USB In and 18 USB Out . When we select higher sampling frequency .
e.g. At the sampling frequency 192KHz , the system will be changed to support 8 USB In and 8 USB Out only dynamically.

I guess that it is possible to use different alternatives settings in USB descriptor to inform HOST. Is my understanding correct ?

Could someone those who have experience to implement such feature to share more information with me ?

Many thinks
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johned
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Postby johned » Mon Jul 17, 2017 10:17 am

Hi,

I would implement this with AN00109: Multiple Firmware Booting : https://www.xmos.com/support/appnotes. You could boot different builds, for your different configurations.
Please note that this might cause problems under Windows because Windows caches the USB device configurations (e.g. number of channels) for a specific VID/PID combination.
You might like to try using a different PID for each configuration which should hopefully resolve this.

Best,
John
dkybchoi
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Postby dkybchoi » Mon Jul 17, 2017 11:37 am

Thanks for your reply. But I think it is different case. We need to change the channel count dynamically, it is not allowed to reboot the unit. Thanks anyway !
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bowerymarc
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Postby bowerymarc » Sun Oct 29, 2017 5:53 am

dkybchoi wrote:We need to change the channel count dynamically, it is not allowed to reboot the unit.

did you ever solve this?

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