i2cdetect(8)

1I2CDETECT(8)                System Manager's Manual               I2CDETECT(8)
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NAME

6       i2cdetect - detect I2C chips
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SYNOPSIS

10       i2cdetect [-y] [-a] [-q|-r] i2cbus [first last]
11       i2cdetect -F i2cbus
12       i2cdetect -V
13       i2cdetect -l
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DESCRIPTION

17       i2cdetect  is  a  userspace  program to scan an I2C bus for devices. It
18       outputs a table with the list of detected devices on the specified bus.
19       i2cbus  indicates  the number or name of the I2C bus to be scanned, and
20       should correspond to one of the busses listed by i2cdetect -l.  The op‐
21       tional  parameters first and last restrict the scanning range (default:
22       from 0x08 to 0x77).
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24       As there is no standard I2C detection command, i2cdetect uses arbitrary
25       SMBus  commands  (namely  SMBus  quick write and SMBus receive byte) to
26       probe for devices. By default, the command used is the one believed  to
27       be  the  safest  for each address. See options -q and -r to change this
28       behavior.
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30       i2cdetect can also be used to query the functionalities of an  I2C  bus
31       (see option -F.)
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WARNING

35       This program can confuse your I2C bus, cause data loss and worse!
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INTERPRETING THE OUTPUT

39       Each  cell  in  the output table will contain one of the following sym‐
40       bols:
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42       • "--". The address was probed but no chip answered.
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44       • "UU". Probing was skipped, because this address is currently  in  use
45         by  a driver. This strongly suggests that there is a chip at this ad‐
46         dress.
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48       • An address number in hexadecimal, e.g. "2d" or "4e". A chip was found
49         at this address.
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OPTIONS

53       -y     Disable  interactive mode. By default, i2cdetect will wait for a
54              confirmation from the user before messing with the I2C bus. When
55              this  flag is used, it will perform the operation directly. This
56              is mainly meant to be used in scripts.
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58       -a     Force scanning of non-regular addresses. Not recommended.
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60       -q     Use SMBus "quick write" command for probing.   Not  recommended.
61              This is known to corrupt the Atmel AT24RF08 EEPROM found on many
62              IBM Thinkpad laptops.
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64       -r     Use SMBus "receive byte" command for probing.  Not  recommended.
65              This  is  known  to lock SMBus on various write-only chips (most
66              notably clock chips at address 0x69).
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68       -F     Display the list of functionalities implemented by  the  adapter
69              and exit.
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71       -V     Display the version and exit.
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73       -l     Output a list of installed busses.
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EXAMPLES

77       List all available I2C busses:
78              # i2cdetect -l
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80       Immediately scan the standard addresses on I2C bus 9 (i2c-9), using the
81       default method for each address (no user confirmation):
82              # i2cdetect -y 9
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84       Query the functionalities of I2C bus 1 (i2c-1):
85              # i2cdetect -F 1
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87       Scan addresses 0x10 to 0x17 on the I2C bus named "SMBus I801 adapter at
88       efa0", using the "receive byte" method, after user confirmation:
89              # i2cdetect -r "SMBus I801 adapter at efa0" 0x10 0x17
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BUGS

93       To  report  bugs  or  send fixes, please write to the Linux I2C mailing
94       list <linux-i2c@vger.kernel.org> with Cc  to  the  current  maintainer:
95       Jean Delvare <jdelvare@suse.de>.
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AUTHOR

103       Frodo Looijaard, Mark D. Studebaker and Jean Delvare
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105       This  manual page was originally written by Aurelien Jarno <aurel32@de‐
106       bian.org>, for the Debian GNU/Linux system.
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110                                 October 2017                     I2CDETECT(8)