i2cdump(8) -- Linux man page



i2cdump - examine I2C registers



i2cdump i2cbus address [mode] [bank [bankreg]]



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



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, 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. 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 general 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 <dmaze@debian.org> for the Debian GNU/Linux system. It was then reviewed by the lm_sensors team and is now part of the lm_sensors source distribution.