i2cdetect - detect I2C chips
i2cdetect -F i2cbus
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
restrict the scanning range (default:
from 0x03 to 0x77).
As there is no standard I2C detection command, i2cdetect uses arbitrary SMBus
commands (namely SMBus quick write and SMBus receive byte) to probe for
devices. By default, the command used is the one believed to be the safest for
each address. See options -q
to change this behavior.
i2cdetect can also be used to query the functionalities of an I2C bus (see
This program can confuse your I2C bus, cause data loss and worse!
Each cell in the output table will contain one of the following symbols:
- "--". The address was probed but no chip
- "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.
- An address number in hexadecimal, e.g. "2d" or
"4e". A chip was found at this address.
- 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.
- Force scanning of non-regular addresses. Not
- Use SMBus "quick write" command for probing. Not
recommended. This is known to corrupt the Atmel AT24RF08 EEPROM found on
many IBM Thinkpad laptops.
- Use SMBus "receive byte" command for probing. Not
recommended. This is known to lock SMBus on various write-only chips (most
notably clock chips at address 0x69).
- Display the list of functionalities implemented by the
adapter and exit.
- Display the version and exit.
- Output a list of installed busses.
Frodo Looijaard, Mark D. Studebaker and Jean Delvare
This manual page was originally written by Aurelien Jarno
<firstname.lastname@example.org>, for the Debian GNU/Linux system.