I2CDETECT(8) System Manager's Manual I2CDETECT(8)NAME
i2cdetect - detect I2C chips
SYNOPSIS
i2cdetect [-y] [-a] [-q|-r] i2cbus [first last]
i2cdetect -F i2cbus
i2cdetect -V
i2cdetect -l
DESCRIPTION
i2cdetect is a userspace program to scan an I2C bus for devices. It outputs a table with the list of detected devices on the specified bus.
i2cbus indicates the number or name of the I2C bus to be scanned, and should correspond to one of the busses listed by i2cdetect -l. The
optional parameters first and last restrict the scanning range (default: from 0x03 to 0x77).
i2cdetect can also be used to query the functionalities of an I2C bus (see option -F.)
WARNING
This program can confuse your I2C bus, cause data loss and worse!
INTERPRETING THE OUTPUT
Each cell in the output table will contain one of the following symbols:
o "--". The address was probed but no chip answered.
o "UU". Probing was skipped, because this address is currently in use by a driver. This strongly suggests that there is a chip at this
address.
o An address number in hexadecimal, e.g. "2d" or "4e". A chip was found at this address.
OPTIONS -y Disable interactive mode. By default, i2cdetect 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 Force scanning of non-regular addresses. Not recommended.
-q Use SMBus "quick write" commands for probing (by default, the command used is the one believed to be the safest for each address).
Not recommended. This is known to corrupt the Atmel AT24RF08 EEPROM found on many IBM Thinkpad laptops.
-r Use SMBus "read byte" commands for probing (by default, the command used is the one believed to be the safest for each address).
Not recommended. This is known to lock SMBus on various write-only chips (most notably clock chips at address 0x69).
-F Display the list of functionalities implemented by the adapter and exit.
-V Display the version and exit.
-l Output a list of installed busses.
SEE ALSO i2cdump(8), sensors-detect(8)AUTHOR
Frodo Looijaard, Mark D. Studebaker and Jean Delvare
This manual page was originally written by Aurelien Jarno <aurel32@debian.org>, for the Debian GNU/Linux system.
April 2008 I2CDETECT(8)
Check Out this Related Man Page
I2CDUMP(8) System Manager's Manual I2CDUMP(8)NAME
i2cdump - examine I2C registers
SYNOPSIS
i2cdump [-f] [-r first-last] [-y] 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.
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 cor-
respond 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 informa-
tion 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.
SEE ALSO i2cset(8), i2cdetect(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.
May 2008 I2CDUMP(8)