1.\" $NetBSD: ubt.4,v 1.6 2006/09/10 20:09:11 plunky Exp $ 2.\" 3.\" Copyright (c) 2006 Itronix Inc. 4.\" All rights reserved. 5.\" 6.\" Written by Iain Hibbert for Itronix Inc. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. The name of Itronix Inc. may not be used to endorse 17.\" or promote products derived from this software without specific 18.\" prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY ITRONIX INC. ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 22.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 23.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL ITRONIX INC. BE LIABLE FOR ANY 24.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 25.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 26.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 27.\" ON ANY THEORY OF LIABILITY, WHETHER IN 28.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 29.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 30.\" POSSIBILITY OF SUCH DAMAGE. 31.\" 32.Dd August 27, 2006 33.Dt UBT 4 34.Os 35.Sh NAME 36.Nm ubt 37.Nd USB Bluetooth driver 38.Sh SYNOPSIS 39.Cd "ubt* at uhub? port ? configuration ? interface ?" 40.Sh DESCRIPTION 41The 42.Nm 43driver provides support for USB Bluetooth dongles 44to the Bluetooth protocol stack. 45.Pp 46USB Bluetooth dongles provide two interfaces, both of which the 47.Nm 48driver claims. 49The second interface is used for Isochronous data and will have 50several alternate configurations regarding bandwidth consumption, 51which can be set using the hw.ubtN.config 52.Xr sysctl 8 53variable. 54The number of alternate configurations is indicated by the value 55in the hw.ubtN.alt_config variable, and the isoc frame size for the current 56configuration is shown in the hw.ubtN.sco_rxsize and hw.ubtN.sco_txsize 57variables. 58.Pp 59By default, configuration 0 is selected, which means that no bandwidth 60is used on the Isochronous interface and no SCO data can be sent. 61Consult the Bluetooth USB specification at https://www.bluetooth.org/ 62for complete instructions on setting bandwidth consumption. 63The following extract may be 64useful as a general guidance though details may differ between manufacturers. 65.Pp 66.Bl -tag -compact -width XXX 67.It 0 68No active voice channels 69.It 1 70One voice channel with 8-bit encoding 71.It 2 72Two voice channels with 8-bit encoding, or one voice channel with 7316-bit encoding. 74.It 3 75Three voice channels with 8-bit encoding 76.It 4 77Two voice channels with 16-bit encoding 78.It 5 79Three voice channels with 16-bit encoding 80.El 81.Sh SEE ALSO 82.Xr bluetooth 4 , 83.Xr uhub 4 , 84.Xr sysctl 8 85.Sh HISTORY 86This 87.Nm 88device driver was originally a character device written by 89.An David Sainty 90and 91.An Lennart Augustsson . 92It was rewritten to support socket based Bluetooth access for 93.Nx 4.0 94by 95.An Iain Hibbert . 96.Sh CAVEATS 97Isochronous data is seemingly not well supported over USB in the current 98system and to get SCO working, you may have to calculate the SCO packet 99size that the stack will use. 100This is the sco_mtu value reported by the 101.Xr btconfig 8 102command, and when combined with the SCO header (3 bytes) should 103fit exactly into an integer number of Isochronous data frames where 104the frame size is indicated by the 105.Sq hw.ubtN.sco_txsize 106sysctl variable. 107.Pp 108For example: I want one voice channel (which is all that is supported, 109for now) so am using configuration #2, with a frame length of 17 110bytes. 111This gives possible values of: 112.Pp 113.Dl "(17 * 1) - 3 = 14" 114.Dl "(17 * 2) - 3 = 31" 115.Dl "(17 * 3) - 3 = 48" 116.Dl "(17 * 4) - 3 = 65" 117.Dl "(17 * 5) - 3 = 82" 118.Dl "etc." 119.Pp 120.Xr btconfig 8 121shows the maximum SCO payload as 64 bytes, so I am using the next smaller 122size of 48, to minimize the overhead of the 3 header bytes. 123.Pp 124The SCO packet size can be changed using the 125.Sq scomtu 126option to 127.Xr btconfig 8 . 128.Pp 129The failure mode is that the USB Bluetooth dongle locks up though 130generally removal/reinsertion will clear the problem. 131.Sh BUGS 132The Isochronous configuration can only be changed when the device is not 133marked up. 134