Bluetooth headset routed over USB on Freerunner: why we need it and what problems i faced

Andy Green andy at
Tue Feb 24 04:03:28 CET 2009

Hash: SHA1

Somebody in the thread at some point said:
| Paul Fertser wrote:
|> Following information is based on AN107 [1] (CSR, 2002, describes SCO
|> configuration for BC-01b and BC-02-External) and experience.
| Please let me reveal myself as the total BT ignoramus that I am:
| Is the bottom line that unidirectional audio (A2DP) over USB to the
| BT device works, but bidirectional audio (SCO) over USB doesn't ?
| And the reason for this is unknown, but you suspect an audio
| routing issue in the BT module ?

WM8753 can't make a routing between it's two digital audio ports (one
goes off to BT module and the other to the CPU).

We can make paths between the analogue ports for the GSM module and
either of the digital ports, so BT for phone calls works and recording
audio works on CPU side.

But for the case we are being an MP3 player, we can't pipe the result
frm the CPU on digital audio interface, to the BT module over its
digital audio interface inside WM8753.

Paul found this USB-based audio input possibility for the BT module that
is semi-standard, but when he tried to pipe the audio down there, it
didn't actually work.  AFAIK nobody has tried that way in OM before so
it's not entirely surprising.

- -Andy
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