NetBSD/share/man/man4/btsco.4
tron 30d6332135 Bluetooth fixes by Iain Hibbert:
Remove bthset(4) device and add btsco(4) in its place. This is an
improved version which is not just for headsets, as it can receive
incoming connections (eg for Hands Free Profile). Update bthset(1)
control utlitiy to relate to new device.
2006-07-26 10:43:01 +00:00

156 lines
4.8 KiB
Groff

.\" $NetBSD: btsco.4,v 1.1 2006/07/26 10:43:02 tron Exp $
.\"
.\" Copyright (c) 2006 Itronix Inc.
.\" All rights reserved.
.\"
.\" Written by Iain Hibbert for Itronix Inc.
.\"
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.\"
.Dd Jul 9, 2006
.Dt BTSCO 4
.Os
.Sh NAME
.Nm btsco
.Nd Bluetooth SCO Audio
.Sh SYNOPSIS
.Cd "btsco* at btdev?"
.Cd "audio* at audiobus?"
.Sh DESCRIPTION
The
.Nm
driver provides support for Bluetooth SCO Audio devices through the
.Xr audio 4
driver, and only supports
playing and recording of 8kHz, 16-bit, 1 channel, signed linear samples.
.Pp
The
.Nm
driver must be configured at run time with the
.Xr btcontrol 8
program. The following properties are used by the
.Nm
driver during autoconfiguration:
.Pp
.Bl -tag -width listenXX
.It local-bdaddr
Local device address.
.It remote-bdaddr
Remote device address.
.It device-type
Should be
.Sq btsco ,
indicating an SCO Audio device.
.It mtu
Packet Size to use, see Caveat section below for details.
.It listen
If this boolean value exists and is true, the
.Nm
device will, on
.Xr open 2 ,
listen for incoming connections from the remote device. Otherwise,
.Nm
will attempt to initiate a connection to the remote device.
.It rfcomm-channel
This integer value is not used directly, but will be stored and passed via the
.Dv BTSCO_INFO
ioctl as below:
.El
.Pp
SCO connections require a baseband connection between the two devices before
they can be created. The
.Nm
driver does not create this, but can provide information to facilitate
an application setting up a control channel prior to use, via the
.Dv BTSCO_INFO
.Xr ioctl 2
call on the mixer device, which returns a
.Ar btsco_info
structure as follows:
.Bd -literal -offset
#include <dev/bluetooth/btsco.h>
struct btsco_info {
bdaddr_t laddr; /* controller bdaddr */
bdaddr_t raddr; /* headset bdaddr */
uint8_t channel; /* RFCOMM channel */
int vgs; /* mixer index speaker */
int vgm; /* mixer index mic */
};
#define BTSCO_INFO _IOR('b', 16, struct btsco_info)
.Ed
.Pp
The
.Nm
driver can be configured to act in Connect or Listen mode. In Connect mode, the
.Nm
driver will initate a connection to the remote device on an
.Xr open 2
call, whereas in Listen mode,
.Xr open 2
will block until the remote device initiates the connection.
.Sh CAVEATS
Isochronous data is seemingly not well supported over USB in the current system
and to get a headset working, you will have to do some research and fine tuning.
.Pp
Look at
.Xr ubt 4
with regards to the
.Xr sysctl 8
settings. Then, you will have to calculate the MTU that the
driver will use. This should be less than the sco_mtu reported by the
.Xr btconfig 8
program, and when combined with the SCO header (3 bytes) should fit exactly into
an integer number of frames, where the frame size is indicated by hw.ubtN.sco_txsize.
.Pp
For example. I want one voice channel (which is all that is supported,
for now) so am using configuration number 2, with a frame length of 17
bytes. My USB dongle says the maximum SCO payload is 64 bytes, so I am
using an MTU of 48 bytes (17 * 3 - 3 = 48).
.Pp
Specify the MTU when you configure the SCO audio device with
.Xr btcontrol 8
and all should be well.
.Pp
The failure mode is that the USB Bluetooth dongle locks
up and requires removal/reinsertion to clear.
.Sh SEE ALSO
.Xr audio 4 ,
.Xr bluetooth 4 ,
.Xr btcontrol 8 ,
.Xr btdev 4 ,
.Xr bthset 1 ,
.Xr ioctl 2
.Sh HISTORY
The
.Nm
driver
was written for
.Nx 4.0
by
.An Iain Hibbert
under the sponsorship of Itronix, Inc.