.\"	$OpenBSD: owsbm.4,v 1.5 2007/05/31 19:19:51 jmc Exp $
.\"
.\" Copyright (c) 2007 Aaron Linville <aaron@linville.org>
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.Dd $Mdocdate: May 31 2007 $
.Dt OWSBM 4
.Os
.Sh NAME
.Nm owsbm
.Nd 1-Wire smart battery monitor device
.Sh SYNOPSIS
.Cd "owsbm* at onewire?"
.Sh DESCRIPTION
The
.Nm
driver provides support for the 1-Wire smart battery monitor.
The sensor possesses a temperature sensor, an A/D converter for measuring both
battery voltage and current, a current accumulator of both incoming and
outgoing current, an elapsed time and 40 bytes of nonvolatile EEPROM.
.Pp
Only the three voltages (VDD, VAD, CR) and temperature are accessible by
the
.Xr sysctl 8
interface.
.Pp
The following chips are supported by the driver:
.Pp
.Bl -bullet -compact -offset indent
.It
Maxim/Dallas DS2438
.El
.Sh MEASURING CURRENT
The sensor does not measure current directly.
Instead it measures the voltage across the Rsens pins.
.Bd -literal -offset indent
I = Voltage CR / Rsens    (where Rsens is in Ohms)
.Ed
.Sh SEE ALSO
.Xr intro 4 ,
.Xr onewire 4 ,
.Xr owtemp 4 ,
.Xr sysctl 8
.Sh HISTORY
The
.Nm
driver first appeared in
.Ox 4.1 .
.Sh AUTHORS
.An -nosplit
The
.Nm
driver was written by
.An Aaron Linville Aq aaron@linville.org .