1I2CSET(8) System Manager's Manual I2CSET(8)
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6 i2cset - set I2C registers
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10 i2cset [-f] [-y] i2cbus chip-address data-address value [mode] [mask]
11 i2cset -V
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15 i2cset is a small helper program to set registers visible through the
16 I2C bus.
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20 -V Display the version and exit.
21 -f Force access to the device even if it is already busy. By
23 default, i2cset will refuse to access a device which is already
24 under the control of a kernel driver. Using this flag is danger‐
25 ous, it can seriously confuse the kernel driver in question. It
26 can also cause i2cset to silently write to the wrong register.
27 So use at your own risk and only if you know what you're doing.
28 -y Disable interactive mode. By default, i2cset will wait for a
30 confirmation from the user before messing with the I2C bus. When
31 this flag is used, it will perform the operation directly. This
32 is mainly meant to be used in scripts.
33 There are four required options to i2cset. i2cbus indicates the number
35 of the I2C bus to be scanned. This number should correspond to one of
36 the busses listed by i2cdetect -l. chip-address specifies the address
37 of the chip on that bus, and is an integer between 0x00 and 0x7F.
38 data-address specifies the address on that chip to write to, and is an
39 integer between 0x00 and 0xFF. value is the value to write to that
40 location on the chip.
41 The mode parameter, if specified, is one of the letters b or w, corre‐
43 sponding to a write size of a single byte or a 16-bit word, respec‐
44 tively. A p can also be appended to the mode parameter to enable PEC.
45 If the mode parameter is omitted, i2cset defaults to byte mode without
46 PEC. The value provided must be within range for the specified data
47 type (0x00-0xFF for bytes, 0x0000-0xFFFF for words).
48 The mask parameter, if specified, describes which bits of value will be
50 actually written to data-address. Bits set to 1 in the mask are taken
51 from value, while bits set to 0 will be read from data-address and thus
52 preserved by the operation.
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56 i2cset can be extremely dangerous if used improperly. It can confuse
57 your I2C bus, cause data loss, or have more serious side effects. Writ‐
58 ing to a serial EEPROM on a memory DIMM (chip addresses between 0x50
59 and 0x57) may DESTROY your memory, leaving your system unbootable! Be
60 extremely careful using this program.
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64 i2cdump(8), isaset(8)
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68 Frodo Looijaard, Mark D. Studebaker, and the lm_sensors group
69 http://www.lm-sensors.org/ This manual page was originally written by
70 David Z Maze <dmaze@debian.org> for the Debian GNU/Linux system. It was
71 then reviewed by the lm_sensors team and is now part of the lm_sensors
72 source distribution.
73 June 2007 I2CSET(8)