i2cdump - examine I2C registers
i2cdump [-y] i2cbus address [mode] [bank [bankreg]]
i2cdump is a small helper program to examine registers visible through
the I2C bus.
-V Display the version and exit.
-y Disable interactive mode. By default, i2cdump 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.
At least two options must be provided to i2cdump. i2cbus indicates the
number of the I2C bus to be scanned. This number should correspond to
one of the busses listed by i2cdetect -l. address indicates the address
to be scanned on that bus, and is an integer between 0x00 and 0x7F. The
mode parameter, if specified, is one of the letters b, w, s, or i, cor-
responding to a read size of a single byte, a 16-bit word, an SMBus
block, an I2C block, respectively. The c mode is a little different, it
reads all bytes consecutively, and is useful for chips that have an
address auto-increment feature. A p can also be appended to the mode
parameter to enable PEC. If the mode parameter is omitted, i2cdump
defaults to byte access without PEC.
The bank and bankreg parameters are useful on the W83781D and similar
chips (at the time of writing, all Winbond and Asus chips). bank is an
integer between 0 and 7, and bankreg is an integer between 0x00 and
0xFF (default value: 0x4E). The W83781D data sheet has more information
on bank selection.
i2cdump can be dangerous if used improperly. Most notably, the c mode
starts with WRITING a byte to the chip. On most chips it will be stored
in the address pointer register, which is OK, but some chips with a
single register or no (visible) register at all will most likely see
this as a real WRITE, resulting in possible misbehavior or corruption.
Do not use i2cdump on random addresses. Anyway, it is of little use
unless you have an idea of what you are looking for and have some gen-
eral knowledge about hardware monitoring chips internals.
i2cset(8), i2cdetect(8), isadump(8)
Frodo Looijaard, Mark D. Studebaker, and the lm_sensors group
http://www.lm-sensors.nu/ This manual page was originally written by
David Z Maze <firstname.lastname@example.org> for the Debian GNU/Linux system. It was
then reviewed by the lm_sensors team and is now part of the lm_sensors
August 2004 I2CDUMP(8)
Man(1) output converted with