| 1 | .TH I2CSET 8 "June 2007" |
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| 2 | .SH "NAME" |
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| 3 | i2cset \- set I2C registers |
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| 4 | |
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| 5 | .SH SYNOPSIS |
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| 6 | .B i2cset |
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| 7 | .RB [ -f ] |
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| 8 | .RB [ -y ] |
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| 9 | .I i2cbus |
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| 10 | .I chip-address |
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| 11 | .I data-address |
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| 12 | .I value |
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| 13 | .RI [ mode ] |
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| 14 | .RI [ mask ] |
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| 15 | .br |
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| 16 | .B i2cset |
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| 17 | .B -V |
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| 18 | |
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| 19 | .SH DESCRIPTION |
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| 20 | i2cset is a small helper program to set registers visible through the I2C |
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| 21 | bus. |
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| 22 | |
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| 23 | .SH OPTIONS |
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| 24 | .TP |
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| 25 | .B -V |
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| 26 | Display the version and exit. |
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| 27 | .TP |
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| 28 | .B -f |
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| 29 | Force access to the device even if it is already busy. By default, i2cset |
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| 30 | will refuse to access a device which is already under the control of a |
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| 31 | kernel driver. Using this flag is dangerous, it can seriously confuse the |
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| 32 | kernel driver in question. It can also cause i2cset to silently write to |
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| 33 | the wrong register. So use at your own risk and only if you know what |
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| 34 | you're doing. |
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| 35 | .TP |
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| 36 | .B -y |
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| 37 | Disable interactive mode. By default, i2cset will wait for a confirmation |
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| 38 | from the user before messing with the I2C bus. When this flag is used, it |
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| 39 | will perform the operation directly. This is mainly meant to be used in |
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| 40 | scripts. |
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| 41 | .PP |
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| 42 | There are four required options to i2cset. \fIi2cbus\fR indicates the number |
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| 43 | of the I2C bus to be scanned. This number should correspond to one of |
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| 44 | the busses listed by \fIi2cdetect -l\fR. \fIchip-address\fR specifies the |
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| 45 | address of the chip on that bus, and is an integer between 0x00 and 0x7F. |
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| 46 | \fIdata-address\fR specifies the address on that chip to write to, and is an |
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| 47 | integer between 0x00 and 0xFF. \fIvalue\fR is the value to write to that |
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| 48 | location on the chip. |
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| 49 | .PP |
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| 50 | The \fImode\fR parameter, if specified, is one of the letters \fBb\fP or |
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| 51 | \fBw\fP, corresponding to a write size of a single byte or a 16-bit word, |
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| 52 | respectively. A \fBp\fP can also be appended to the \fImode\fR parameter to |
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| 53 | enable PEC. If the \fImode\fR parameter is omitted, i2cset defaults to byte |
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| 54 | mode without PEC. The \fIvalue\fR provided must be within range for the |
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| 55 | specified data type (0x00-0xFF for bytes, 0x0000-0xFFFF for words). |
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| 56 | .PP |
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| 57 | The \fImask\fR parameter, if specified, describes which bits of \fIvalue\fR |
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| 58 | will be actually written to \fIdata-address\fR. Bits set to 1 in the mask |
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| 59 | are taken from \fIvalue\fR, while bits set to 0 will be read from |
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| 60 | \fIdata-address\fR and thus preserved by the operation. |
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| 61 | |
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| 62 | .SH WARNING |
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| 63 | i2cset can be extremely dangerous if used improperly. It can confuse your |
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| 64 | I2C bus, cause data loss, or have more serious side effects. Writing to |
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| 65 | a serial EEPROM on a memory DIMM (chip addresses between 0x50 and 0x57) may |
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| 66 | DESTROY your memory, leaving your system unbootable! Be extremely careful |
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| 67 | using this program. |
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| 68 | |
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| 69 | .SH SEE ALSO |
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| 70 | i2cdump(8), isaset(8) |
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| 71 | |
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| 72 | .SH AUTHOR |
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| 73 | Frodo Looijaard, Mark D. Studebaker, and the lm_sensors group |
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| 74 | http://www.lm-sensors.org/ |
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| 75 | This manual page was originally written by David Z Maze <dmaze@debian.org> for |
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| 76 | the Debian GNU/Linux system. It was then reviewed by the lm_sensors team and |
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| 77 | is now part of the lm_sensors source distribution. |
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