.Dd Jule 28, 2013
.Dt VUSB-I2CDETECT 1
.Os
.
.
.Sh NAME
.
.Nm vusb-i2cdetect
.Nd detect I2C devices
.
.
.Sh SYNOPSIS
.
.Nm
.
.
.Sh VERSION
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This manual documents
.Nm
UNRELEASED
.
.
.Sh DESCRIPTION
.
.Nm
scans a vusb-i2c bus for connected devices and prints a result table to its
standard output. A
.Qq --
entry means no device responded, while a hexadecimal address means there is
a device acknowledging that address.
.
.Pp
.
In detail, for each I2C address between 0x00 and 0x7f (even the special ones),
the following is done:

.Bl -bullet
.
.It
the bus is reset (START condition)
.
.It
an address (with the read byte set) is transmitted
.
.It
the transmission is terminated without reading any data (STOP condition)
.
.El

If SDA is pulled low in the ACK cycle of the address transmission, it is
considered to be a device listening for that address. If
.Nm
reports devices on all checked addresses, this may indicate a stuck SDA line,
either caused by a hardware bug or a malfunctioning I2C device.
.
.Sh AUTHOR
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Copyright (C) 2013 by Birte Friesel
.Aq derf@finalrewind.org
.
.Sh LICENSE
.
to be determined (BSD-ish)