xref: /freebsd/usr.sbin/i2c/i2c.8 (revision 069ac184) 
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26.Dd May 22, 2019
27.Dt I2C 8
28.Os
29.Sh NAME
30.Nm i2c
31.Nd test I2C bus and slave devices
32.Sh SYNOPSIS
33.Nm
34.Cm -a Ar address
35.Op Fl f Ar device
36.Op Fl d Ar r|w
37.Op Fl w Ar 0|8|16|16LE|16BE
38.Op Fl o Ar offset
39.Op Fl c Ar count
40.Op Fl m Ar tr|ss|rs|no
41.Op Fl b
42.Op Fl v
43.Nm
44.Cm -h
45.Nm
46.Cm -i
47.Op Fl v
48.Op Ar cmd ...
49.Op Ar -
50.Nm
51.Cm -r
52.Op Fl f Ar device
53.Op Fl v
54.Nm
55.Cm -s
56.Op Fl f Ar device
57.Op Fl n Ar skip_addr
58.Op Fl v
59.Sh DESCRIPTION
60The
61.Nm
62utility can be used to perform raw data transfers (read or write) to devices
63on an I2C bus.
64It can also scan the bus for available devices and reset the I2C controller.
65.Pp
66The options are as follows:
67.Bl -tag -width ".Fl d Ar direction"
68.It Fl a Ar address
697-bit address on the I2C device to operate on (hex).
70.It Fl b
71binary mode - when performing a read operation, the data read from the device
72is output in binary format on stdout.
73.It Fl c Ar count
74number of bytes to transfer (decimal).
75.It Fl d Ar r|w
76transfer direction: r - read, w - write.
77Data to be written is read from stdin as binary bytes.
78.It Fl f Ar device
79I2C bus to use (default is /dev/iic0).
80.It Fl i
81Interpreted mode
82.It Fl h
83Help
84.It Fl m Ar tr|ss|rs|no
85addressing mode, i.e., I2C bus operations performed after the offset for the
86transfer has been written to the device and before the actual read/write
87operation.
88.Bl -tag -compact -offset indent
89.It Va tr
90complete-transfer
91.It Va ss
92stop then start
93.It Va rs
94repeated start
95.It Va no
96none
97.El
98Some I2C bus hardware does not provide control over the individual start,
99repeat-start, and stop operations.
100Such hardware can only perform a complete transfer of the offset and the
101data as a single operation.
102The
103.Va tr
104mode creates control structures describing the transfer and submits them
105to the driver as a single complete transaction.
106This mode works on all types of I2C hardware.
107.It Fl n Ar skip_addr
108address(es) to be skipped during bus scan.
109One or more addresses ([0x]xx) or ranges of addresses
110([0x]xx-[0x]xx or [0x]xx..[0x]xx) separated by commas or colons.
111.It Fl o Ar offset
112offset within the device for data transfer (hex).
113The default is zero.
114Use
115.Dq -w 0
116to disable writing of the offset to the slave.
117.It Fl r
118reset the controller.
119.It Fl s
120scan the bus for devices.
121.It Fl v
122be verbose.
123.It Fl w Ar 0|8|16|16LE|16BE
124device offset width (in bits).
125This is used to determine how to pass
126.Ar offset
127specified with
128.Fl o
129to the slave.
130Zero means that the offset is ignored and not passed to the slave at all.
131The endianness defaults to little-endian.
132.El
133.Sh INTERPRETED MODE
134When started with
135.Fl i
136any remaining arguments are interpreted as commands, and
137if the last argument is '-', or there are no arguments,
138commands will (also) be read from stdin.
139.Pp
140Available commands:
141.Bl -tag -compact
142.It 'r' bus address [0|8|16|16LE|16BE] offset count
143Read command, count bytes are read and hexdumped to stdout.
144.It 'w' bus address [0|8|16|16LE|16BE] offset hexstring
145Write command, hexstring (white-space is allowed) is written to device.
146.It 'p' anything
147Print command, the entire line is printed to stdout.  (This can be used
148for synchronization.)
149.El
150.Pp
151All numeric fields accept canonical decimal/octal/hex notation.
152.Pp
153Without the
154.Fl v
155option, all errors are fatal with non-zero exit status.
156.Pp
157With the
158.Fl v
159option, no errors are fatal, and all commands will return
160either "OK\en" or "ERROR\en" on stdout.
161In case of error, detailed diagnostics will precede that on stderr.
162.Pp
163Blank lines and lines starting with '#' are ignored.
164.Sh EXAMPLES
165.Bl -bullet
166.It
167Scan the default bus (/dev/iic0) for devices:
168.Pp
169i2c -s
170.It
171Scan the default bus (/dev/iic0) for devices and skip addresses
1720x45 to 0x47 (inclusive) and 0x56.
173.Pp
174i2c -s -n 0x56,45-47
175.It
176Read 8 bytes of data from device at address 0x56 (e.g., an EEPROM):
177.Pp
178i2c -a 0x56 -d r -c 8
179.It
180Write 16 bytes of data from file data.bin to device 0x56 at offset 0x10:
181.Pp
182i2c -a 0x56 -d w -c 16 -o 0x10 -b < data.bin
183.It
184Copy 4 bytes between two EEPROMs (0x56 on /dev/iic1 to 0x57 on /dev/iic0):
185.Pp
186i2c -a 0x56 -f /dev/iic1 -d r -c 0x4 -b | i2c -a 0x57 -f /dev/iic0 -d w -c 4 -b
187.It
188Reset the controller:
189.Pp
190i2c -f /dev/iic1 -r
191.It
192Read 8 bytes at address 24 in an EEPROM:
193.Pp
194i2c -i 'r 0 0x50 16BE 24 8'
195.It
196Read 2x8 bytes at address 24 and 48 in an EEPROM:
197.Pp
198echo 'r 0 0x50 16BE 48 8' | i2c -i 'r 0 0x50 16BE 24 8' -
199.El
200.Sh WARNING
201Many systems store critical low-level information in I2C memories, and
202may contain other I2C devices, such as temperature or voltage sensors.
203Reading these can disturb the firmware's operation and writing to them
204can "brick" the hardware.
205.Sh SEE ALSO
206.Xr iic 4 ,
207.Xr iicbus 4
208.Xr smbus 4
209.Sh HISTORY
210The
211.Nm
212utility appeared in
213.Fx 8.0 .
214.Sh AUTHORS
215.An -nosplit
216The
217.Nm
218utility and this manual page were written by
219.An Bartlomiej Sieka Aq Mt tur@semihalf.com
220and
221.An Michal Hajduk Aq Mt mih@semihalf.com .
222.Pp
223.An Poul-Henning Kamp Aq Mt phk@FreeBSD.org
224added interpreted mode.
225