NAME

       i2cdump - examine I2C registers

SYNOPSIS

       i2cdump [-f] [-r first-last] [-y] [-a] i2cbus address [mode [bank [bankreg]]]
       i2cdump -V

DESCRIPTION

       i2cdump is a small helper program to examine registers visible through the I2C bus.

OPTIONS

       -V     Display the version and exit.

       -f     Force access to the device even if it is already busy. By default, i2cdump 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 i2cdump to return invalid
              results. So use at your own risk and only if you know what you're doing.

       -r first-last
              Limit the range of registers being accessed. This option is only available with modes b, w, c  and
              W. For mode W, first must be even and last must be odd.

       -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.

       -a     Allow using addresses between 0x00 - 0x02 and 0x78 - 0x7f. Not recommended.

       At  least  two options must be provided to i2cdump. 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. address  indicates
       the address to be scanned on that bus, and is an integer between 0x03 and 0x77.

       The  mode parameter, if specified, is one of the letters b, w, s, or i, corresponding 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,
       such  as  EEPROMs. The W mode is also special, it is similar to w except that a read command will only be
       issued on even register addresses; this is again mainly useful for EEPROMs.

       A p can also be appended to the mode parameter (except for i and W) 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.

WARNING

       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 good knowledge of the chip you're working with and an idea of what you are looking for.

EXAMPLES

       Dump the whole contents of I2C device at 7-bit address 0x50 on bus 9  (i2c-9),  using  the  default  read
       method (byte mode), after user confirmation:
              # i2cdump 9 0x50

       Immediately dump the whole contents of I2C device at 7-bit address 0x50 on bus 9 (i2c-9), using I2C block
       read transactions (no user confirmation):
              # i2cdump -y 9 0x50 i
       If the device is an EEPROM, the output would typically be the same as output of the previous example.

       Dump  registers  0x00 to 0x3f of the I2C device at 7-bit address 0x2d on bus 1 (i2c-1), using the default
       read method (byte mode), after user confirmation:
              # i2cdump -r 0x00-0x3f 1 0x2d

       Dump the registers of the SMBus device at address 0x69 on bus 0  (i2c-0),  using  one  SMBus  block  read
       transaction with error checking enabled, after user confirmation:
              # i2cdump 0 0x69 sp

SEE ALSO

       i2cdetect(8), i2cget(8), i2cset(8), i2ctransfer(8), isadump(8)

AUTHOR

       Frodo Looijaard, Mark D. Studebaker and Jean Delvare

       This  manual  page  was  originally  written  by David Z Maze <dmaze@debian.org> for the Debian GNU/Linux
       system.

                                                  October 2017                                        I2CDUMP(8)