NAME
i2cget - read from I2C/SMBus chip registers
SYNOPSIS
i2cget [-f] [-y] i2cbus chip-address [data-address [mode]]
i2cget -V
DESCRIPTION
i2cget is a small helper program to read registers visible through the
I2C bus (or SMBus).
OPTIONS
-V Display the version and exit.
-f Force access to the device even if it is already busy. By
default, i2cget will refuse to access a device which is already
under the control of a kernel driver. Using this flag is
dangerous, it can seriously confuse the kernel driver in
question. It can also cause i2cget to return an invalid value.
So use at your own risk and only if you know what you’re doing.
-y Disable interactive mode. By default, i2cget will wait for a
confirmation from the user before messing with the I2C bus. When
this flag is used, it will perform the operation directly. This
is mainly meant to be used in scripts. Use with caution.
There are two required options to i2cget. i2cbus indicates the number
or name of the I2C bus to be scanned. This number should correspond to
one of the busses listed by i2cdetect -l. chip-address specifies the
address of the chip on that bus, and is an integer between 0x03 and
0x77.
data-address specifies the address on that chip to read from, and is an
integer between 0x00 and 0xFF. If omitted, the currently active
register will be read (if that makes sense for the considered chip).
The mode parameter, if specified, is one of the letters b, w or c,
corresponding to a read byte data, a read word data or a write
byte/read byte transaction, respectively. A p can also be appended to
the mode parameter to enable PEC. If the mode parameter is omitted,
i2cget defaults to a read byte data transaction, unless data-address is
also omitted, in which case the default (and only valid) transaction is
a single read byte.
WARNING
i2cget can be extremely dangerous if used improperly. I2C and SMBus are
designed in such a way that an SMBus read transaction can be seen as a
write transaction by certain chips. This is particularly true if
setting mode to cp (write byte/read byte with PEC). Be extremely
careful using this program.
SEE ALSO
i2cdump(8), i2cset(8)
AUTHOR
Jean Delvare
This manual page was strongly inspired from those written by David Z
Maze for i2cset.
May 2008