OWSBM(4)                  OpenBSD Programmer's Manual                 OWSBM(4)

NAME
     owsbm - 1-Wire smart battery monitor device

SYNOPSIS
     owsbm* at onewire?

DESCRIPTION
     The owsbm 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.

     Only the three voltages (VDD, VAD, CR) and temperature are accessible by
     the sysctl(8) interface.

     The following chips are supported by the driver:

           o   Maxim/Dallas DS2438

MEASURING CURRENT
     The sensor does not measure current directly.  Instead it measures the
     voltage across the Rsens pins.

           I = Voltage CR / Rsens    (where Rsens is in Ohms)

SEE ALSO
     intro(4), onewire(4), owtemp(4), sysctl(8)

HISTORY
     The owsbm driver first appeared in OpenBSD 4.1.

AUTHORS
     The owsbm driver was written by Aaron Linville <aaron@linville.org>.

OpenBSD 4.7                      May 31, 2007                                1
