root/lm-sensors/branches/lm-sensors-2.10/doc/chips/lm85

Kernel driver `lm85.o'
======================

Status: Complete and somewhat tested

Supported chips:
  * National Semiconductor LM85 (B and C versions)
    Prefix: 'lm85'
    Addresses scanned: I2C 0x2c, 0x2d, 0x2e
    Datasheet: http://www.national.com/pf/LM/LM85.html
  * Analog Devices ADM1027
    Prefix: 'adm1027'
    Addresses scanned: I2C 0x2c, 0x2d, 0x2e
    Datasheet: http://www.analog.com/en/prod/0,,766_825_ADM1027,00.html
  * Analog Devices ADT7463
    Prefix: 'adt7463'
    Addresses scanned: I2C 0x2c, 0x2d, 0x2e
    Datasheet: http://www.analog.com/en/prod/0,,766_825_ADT7463,00.html
  * SMSC EMC6D100, SMSC EMC6D101
    Prefix: 'emc6d100'
    Addresses scanned: I2C 0x2c, 0x2d, 0x2e
    Datasheet: http://www.smsc.com/main/tools/discontinued/6d100.pdf
  * SMSC EMC6D102, SMSC EMC6D101
    Prefix: 'emc6d102'
    Addresses scanned: I2C 0x2c, 0x2d, 0x2e
    Datasheet: http://www.smsc.com/main/catalog/emc6d102.html

Authors:
      Philip Pokorny <ppokorny@penguincomputing.com>
      Frodo Looijaard <frodol@dds.nl>
      Richard Barrington <rich_b_nz@clear.net.nz>


Module Parameters
-----------------

* force: short array (min = 1, max = 48)
  List of adapter,address pairs to assume to be present.  Autodetection
  of the target device will still be attempted.  Use one of the more
  specific force directives below if this doesn't detect the device.
* force_lm85b: short array (min = 1, max = 48)
  List of adapter,address pairs which are unquestionably assumed to contain
  a `lm85-B' chip
* force_lm85c: short array (min = 1, max = 48)
  List of adapter,address pairs which are unquestionably assumed to contain
  a `lm85-C' chip
* force_adm1027: short array (min = 1, max = 48)
  List of adapter,address pairs which are unquestionably assumed to contain
  a `adm1027' chip
* force_adt7463: short array (min = 1, max = 48)
  List of adapter,address pairs which are unquestionably assumed to contain
  a `adt7463' chip
* ignore: short array (min = 1, max = 48)
  List of adapter,address pairs not to scan
* ignore_range: short array (min = 1, max = 48)
  List of adapter,start-addr,end-addr triples not to scan
* probe: short array (min = 1, max = 48)
  List of adapter,address pairs to scan additionally
* probe_range: short array (min = 1, max = 48)
  List of adapter,start-addr,end-addr triples to scan additionally


Description
-----------

This driver implements support for the National Semiconductor LM85
and compatible chips including the Analog Devices ADM1027 and ADT7463,
and SMSC EMC6D100, EMC6D101 and EMC6D102.

The LM85 uses the 2-wire interface compatible with the SMBUS 2.0
specification.  Using an analog to digital converter it measures three
(3) temperatures and five (5) voltages.  It has four (4) 16-bit
counters for measuring fan speed.  Five (5) digital inputs are
provided for sampling the VID signals from the processor to the VRM.
Lastly, there are three (3) PWM outputs that can be used to control
fan speed.

The voltage inputs have internal scaling resistors so that the
following voltage can be measured without external resistors:

   2.5V, 3.3V, 5V, 12V, and CPU core voltage (2.25V)

The temperatures measured are one internal diode, and two remote
diodes.  Remote 1 is generally the CPU temperature.  These inputs are
designed to measure a thermal diode like the one in a Pentium 4
processor in a socket 423 or socket 478 package.  They can also
measure temperature using a transistor like the 2N3904.

A sophisticated control system for the PWM outputs is designed into
the LM85 that allows fan speed to be adjusted automatically based on
any of the three temperature sensors.  Each PWM output is individually
adjustable and programmable.  Once configured, the LM85 will adjust
the PWM outputs in response to the measured temperatures without
further host intervention.  This feature can also be disabled for
manual control of the PWM's.

Each of the measured inputs (voltage, temperature, fan speed) has
corresponding high/low limit values.  The LM85 will signal an ALARM if
any measured value exceeds either limit.

The LM85 samples all inputs continuously.  The lm85 driver will not
read the registers more often than once a second.  Further, configuration
data is only read once each 5 minutes.  There is twice as much config
data as measurements, so this would seem to be a worthwhile
optimization.

Special Features

The LM85 has four fan speed monitoring modes.  The ADM1027 has only
two.  Both have special circuitry to compensate for PWM interactions
with the TACH signal from the fans.  The ADM1027 can be configured to
measure the speed of a two wire fan, but the input conditioning
circuitry is different for 3-wire and 2-wire mode.  For this reason,
the 2-wire fan modes are not exposed to user control.  The BIOS should
initialize them to the correct mode.  If you've designed your own
ADM1027, you'll have to modify the init_client function and add an
insmod parameter to set this up.

To smooth the response of fans to changes in temperature, the LM85 has
an optional filter for smoothing temperatures.  The ADM1027 has the
same config option but uses it to rate limit the changes to fan speed
instead.  In libsensors, we associate the smoothing feature with a
zone in the LM85 and with a PWM in the ADM1027.

The ADM1027 and ADT7463 have a 10-bit ADC and can therefore measure
temperatures with 0.25 degC resolution.  They also provide an offset to
the temperature readings that is automatically applied during
measurement.  This offset can be used to zero out any errors due to
traces and placement.  The documentation says that the offset is in
0.25 degC steps, but in initial testing of the ADM1027 it was 1.00
degC steps.  Analog Devices has confirmed this "bug".  The ADT7463 is
reported to work as described in the documentation.  Accordingly, the
driver currently reports 1.00 degC steps for the ADM1027 and 0.25 degC
steps for the ADT7463.  If you have an ADT7463, please confirm to the
LM85 maintainer that the temperature offset works as implemented.

The ADT7463 has a THERM asserted counter.  This counter has a 22.76ms
resolution and a range of 5.8 seconds.  The driver implements a 31-bit
accumulator of the counter value to extend the range to over a year.
The counter will stay at it's max value until read.  If you want to
insure no counts get lost, you need to trigger the driver to read the
counter every 5 seconds.  You can do this by reading just the
therm_signal value.  The driver implements reads of 'therm_signal'
without reading the other values for speed.  A background shell script
like:

    #!/bin/bash
    while [ 1 ] ; do
       cat /proc/sys/dev/sensors/adt7463-*/therm_signal > /dev/null
       sleep 5
    done

Or if you want to record the values:

    #!/bin/bash
    last=0
    while [ 1 ] ; do
       read tlim total ovfl < /proc/sys/dev/sensors/adt7463-*/therm_signal
       if [ $total -gt $last ]; then
          echo $(date) - $tlim $total $ovfl
          last=$total
       fi
       sleep 5;
    done

Either script should insure no counts are lost.

See the vendor datasheets for more information.  There is application
note from National (AN-1260) with some additional information about
the LM85.  The Analog Devices datasheet is very detailed and describes
a procedure for determining an optimal configuration for the automatic
PWM control.

Hardware Configurations
-----------------------

The LM85 can be jumpered for 3 different SMBus addresses.  There are
no other hardware configuration options for the LM85.

The lm85 driver detects both LM85B and LM85C revisions of the chip.
See the datasheet for a complete description of the differences.
Other than identifying the chip, the driver behaves no differently
with regard to these two chips.  The LM85B is recommended for new
designs.

The ADM1027 and ADT7463 chips have an optional SMBALERT output that
can be used to signal the chipset in case a limit is exceeded or the
temperature sensors fail.  Individual sensor interrupts can be masked
with 'alarm_mask' so they won't trigger SMBALERT.  The SMBALERT output
if configured replaces one of the other functions (PWM2 or IN0).  The
driver will print a message if the BIOS has configured this option
when the chip is detected.

The ADT7463 also has an optional THERM output/input which can be
connected to the processor PROC_HOT output.  If available, the autofan
control dynamic Tmin feature can be enabled to keep the system
temperature within spec (just?!) with the least possible fan noise.

Configuration Notes
-------------------

The voltage, temperature and fan inputs are available in libsensors
and the sensors executable.  In addition, the automatic control of the
PWM outputs can also be configured via sensors.conf.  This
configuration is described below:

* Temperatures and Zones

Each temperature sensor is associated with a Zone.  There are three
sensors and therefore three zones.  Each zone has the following
temperature configuration points:

    Limit temp    -- Temperature at which the fan will turn on
                     [ absolute deg C from 0.0 to 127.0 ]
                     [ sensors.conf:   zone#_limit ]
    Hysteresis    -- Degrees below the limit that fan will remain
                     on before turning off.
                     [ relative C from 0.0 to -15.0 ]
                     [ sensors.conf:   zone#_hyst ]
    Range         -- Degrees above the limit over which the fan
                     PWM will be adjusted (from PWM_MIN to 100%)
                     [ relative deg C from 2.0 to 80.0 ]
                     [ sensors.conf:   zone#_range ]
    Critical temp -- Temperature above which other fans will be
                     forced to 100% PWM
                     [ absolute deg C from 0.0 to 127.0 ]
                     [ sensors.conf:   zone#_critical ]

** Temperature Range for a Zone

The RANGE value for a given zone can have one of 16 different values
in an approximately logrithmic spacing:
Selecting a RANGE not in this list will cause the next larger range to
be used.

    Temperature ranges:    2.0, 2.5, 3.3, 4.0, 5.0, 6.6, 8.0, 10.0,
      (in deg C)           13.3, 16.0, 20.0, 26.6, 32.0, 40.0, 53.3,
                           80.0

* Temperature Smoothing or Acoustic Enhancement

The LM85 and ADM1027 use this value in different ways.  In the LM85
it's used to filter the temperature input of a zone.  In this way, it
affects all PWM's controlled by that zone temperature.  In the
ADM1027, it limits the rate of change in fan speed.  Thus it is part
of the PWM control algorithm.

    Smooth filter -- Optional filter constant to smooth the system
                     response to temperature spikes.  It either
                     filters the measured temperatures or limits the
                     rate of change of fan speed.  This improves
                     the system by limiting rapid changes in fan
                     speed.
                     [ seconds from 0.8 to 35.0 or 0.0 for OFF ]
                     [ sensors.conf:   zone#_smooth or pwm#_smooth ]

The smoothing can be disabled, or enabled and set to one of the values
listed below.  Selecting a filter time constant not on this list will
cause the next smaller value to be used.  Setting the time constant to
0 will disable the filtering.

    Filter time constant:  35.0, 17.6, 11.8, 7.0, 4.4, 3.0, 1.6, 0.8
      (in seconds)

* PWM Control

There are three PWM outputs.  The LM85 datasheet suggests that the
pwm3 output control both fan3 and fan4.  Each PWM can be individually
configured and assigned to a zone for it's control value.  Each PWM can be
configured individually according to the following options.

    Spinup time   -- When turning on a fan that was off, the PWM will
                     temporarily be set to 100% for this length of
                     time to insure the fan starts spinning.
                     [ seconds from 0.0 to 4.0 ]
                     [ sensors.conf:  pwm#_spinup ]
    Minimum PWM   -- This is the PWM value at the limit temp of the
                     referenced zone.
                     [ PWM value from 0.0 to 255.0 ]
                     [ sensors.conf:  pwm#_min ]
    Frequency     -- This is the base frequency of the PWM output.
                     [ Hz from 10.0 to 98.0 ]
                     [ sensors.conf:  pwm#_freq ]
    Min/Off flag  -- This flag determines if the PWM will be off or
                     "min PWM" below the limit temperature.
                     [ 0.0 means PWM off (0%) below limit ]
                     [ sensors.conf:  pwm#_min_ctl ]
    Invert flag   -- This flag causes the PWM output to be inverted.
                     If inverted, a PWM setting of 0 will be full on
                     and 100 will be off.
                     [ 0.0 means PWM is "normal" ]
                     [ sensors.conf:  pwm#_invert ]

** Spinup Time

Spinup time can be one of eight (8) values.  Selecting a spinup time
not on this list will result in the next larger spinup time being
selected.  Note, the value 0.2 actually results in a setting of 0.250
seconds.

    Spinup Time     0.0, 0.1, 0.2, 0.4, 0.7, 1.0, 2.0, 4.0
      (in seconds)

** PWM Frequency

The base frequency of the PWM can be controlled.  The frequency can be
set to one of the following 8 values.  Setting the frequency to a
value not on this list, will result in the next higher frequency being
selected.  The actual device frequency may vary slightly from this
specification as designed by the manufacturer.  Consult the datasheet
for more details.

    PWM Frequency   10.0, 15.0, 23.0, 30.0, 38.0, 47.0, 62.0, 98.0
      (in Hz)

** Min/Off Flag

Below the temperature "Limit - Hysteresis" from the controlling zone,
the PWM can turn off (set to 0) or it can stay at the minimum PWM
value.  Setting this flag to 1 will cause the PWM value to be the
"Minimum PWM" value below this limit.  Setting it to 0 will set the
PWM to 0 (off) below that limit.

NOTE: It has been reported that there is a bug in the LM85 that causes
the Min/Off flag to be associated with the zones not the PWMs.  This
contradicts all the published documentation.  Setting pwm#_min_ctl in
this case actually affects all PWMs controlled by zone '#'.

** Invert Flag

The PWM output can be inverted.  This may be useful if the fan power
circuitry is inverted. (A low output turns on power and a high output
turns off power to the fan).  Alternatively, if a slower fan speed is
needed for higher temperatures, this could be set.

Setting this flag to 1 will invert the PWM output.  A value of 0
does not invert the PWM output.

* PWM Controlling Zone selection

PWM's can be controlled by zones according to the following
configuration choices:

   Value     Meaning
  ------  ------------------------------------------------
      1    Controlled by Zone 1
      2    Controlled by Zone 2
      3    Controlled by Zone 3
     23    Controlled by higher temp of Zone 2 or 3
    123    Controlled by highest temp of Zone 1, 2 or 3
      0    PWM alwasy 0%  (off)
     -1    PWM always 100%  (full on)
     -2    Manual control (write to 'pwm#' to set)

These are specified in sensors.conf using 'pwm#_zone'

* /proc Interface

These values can also be set using the /proc interface.  The following
files contain the above settings in the order listed below:

    Name         Values
   ---------- ----------------------------------------------------
    zone#      Limit, Hysteresis, Range, Critical
    pwm#_cfg   Spinup, PWM at low limit, Frequency, Min/Off, Invert
    pwm#_zone  Control Zone choice
    smooth#    Filtering

The National LM85's have two vendor specific configuration
features.  Tach. mode and Spinup Control.  For more details on these,
see the LM85 datasheet or Application Note AN-1260.

    Name           Values
   ------------ --------------------------------------------------
    tach_mode    For best fan speed measurement when PWM's are in use,
                 the Tach Mode should be set to 2 for all three (Fan's
                 3 and 4 share a config setting) config values.  If
                 PWM's are not in use or not wired to control fan
                 speed, mode 0 or 1 may be better.
                 [ sensors.conf:   fan#_tach_mode ]
    spinup_ctl   Setting spinup_ctl to 1 will modify the fan spinup
                 algorithm.  Instead of setting the PWM to 100% for
                 the configured period of time, it will be set to 100%
                 until the measured RPM is greater than the RPM limit
                 register or the time period elapses.
                 [ sensors.conf:   pwm#_spinup_ctl ]

The Analog Devices ADM1027 has several vendor specific enhancements.
The number of pulses-per-rev of the fans can be set, Tach monitoring
can be optimized for PWM operation, and an offset can be applied to
the temperatures to compensate for systemic errors in the
measurements.

    Name           Values
   ------------ --------------------------------------------------
    tach_mode    For best fan speed measurement when PWM's are in use,
                 the Tach Mode should be set to 0.  If PWM's are not
                 in use or not wired to control fan speed, a mode of 1
                 can be selected.  This will also increase the rate
                 of fan speed measurement from 1 per second to 4 per
                 second.
                 [ sensors.conf:   fan#_tach_mode ]
    fan_ppr      You can set the pulses per rev to 1, 2, 3 or 4 so
                 that fan speeds don't have to be scaled.
                 [ sensors.conf:   fan#_ppr ]
    temp#_offset This is the value to be added or subtracted from the
                 measured temperature before reporting it.  This also
                 affects the PWM control algorithms.
                 [ sensors.conf:   temp#_offset ]

In addition to the ADM1027 features, the ADT7463 also has Tmin control
and THERM asserted counts.  Automatic Tmin control acts to adjust the
Tmin value to maintain the measured temperature sensor at a specified
temperature.  There isn't much documentation on this feature in the
ADT7463 data sheet.   The following values control this feature.
(These are not available via sensors.conf)

    Enable Flag   -- When set to 1, the Tmin control is enabled.  When
                     set to 0, Tmin will remain unchanged.
                     [ 1 means Tmin control is enabled ]
                     [ sensors.conf:  none ]
    Control Loop  -- This value sets the cycle time of the control
                     loop which adjusts the Tmin value.  The mapping
                     from raw value to loop period is non-linear.
                     [ Raw value from 0 to 7 (4sec) ]
                     [ sensors.conf:  none ]
    Set on THERM  -- If enabled, this causes the operating point to be
                     set from the current temperature when THERM is
                     asserted.  If THERM is connected to a PROC_HOT
                     signal, this can automatically set the operating
                     point to the highest value that is within spec.
                     allowing the lowest/quietest fan speed possible.
                     [ 1 means set op-point on THERM asserted ]
                     [ sensors.conf:  none ]
    Target Temp   -- This is the target temperature.  Tmin will be
                     adjusted to keep the measured temperature at this
                     value.
                     [ degC -127 to 127 degC ]
                     [ sensors.conf:  none ]

The THERM signal monitoring has three parameters:

    THERM Limit   -- How long THERM can be asserted before an ALARM is
                     triggered.
                     [ 22.7 ms counts ]
                     [ sensors.conf:  none ]
    THERM Total   -- How long THERM has been asserted since the driver
                     was loaded.
                     [ 22.7 ms counts ]
                     [ sensors.conf:  none ]
    Overflows     -- How many times the THERM counter was read with a
                     max value indicating it overflowed.
                     [ count ]
                     [ sensors.conf:  none ]

These values are available via /proc under the following names in the
listed order.

    Name           Values
   ------------ --------------------------------------------------
    tmin_ctl#    Enable, Control Period, Set on THREM, Target
    therm_signal Limit, Total, Overflows


* Sample sensors.conf Config File

Here is a sample LM85 chip config for sensors.conf

--------- cut here ---------
chip "lm85c-*" "adm1027-*" "adt7463-*" "lm85-*" "lm85b-*"

# Voltage inputs
   label in0   "V1.5"      # AGP on Intel S845WD1-E
   label in1   "VCore"
   label in2   "V3.3"
   label in3   "V5"
   label in4   "V12"

# Temperature inputs
   label temp1  "CPU"
   label temp2  "Board"
   label temp3  "Remote"

# Fan inputs
   label fan1   "CPU_Fan"
   label fan2   "Fan2"
   label fan3   "Fan3"
   label fan4   "Fan4"

# PWM Outputs
   label pwm1   "CPU_PWM"
   label pwm2   "Fan2_PWM"
   label pwm3   "Fan3_PWM"

# Voltage scaling is done on-chip.  No 'compute' directive
#    should be necessary.  If in0 has external scaling set
#    it here.

#   compute in0  @ * 2.5,   @ / 2.5

# Adjust fans speeds for actual pulses per rev
   compute fan1  @ * 2,  @ / 2    # 1 pulse per rev
#  set fan1_ppr  1                # ADM1027 or ADT7463
   compute fan2  @ / 2,  @ * 2    # 4 pulse per rev
#  set fan2_ppr  4                # ADM1027 or ADT7463

# Set VRM version
   set vrm  9.1   # Pentium 4

# Set voltage limits
   set in0_min  1.5 * 0.95
   set in0_max  1.5 * 1.05
   set in1_min  vid * 0.95
   set in1_max  vid * 1.05
   set in2_min  3.3 * 0.95
   set in2_max  3.3 * 1.05
   set in3_min  5.0 * 0.95
   set in3_max  5.0 * 1.05
   set in4_min   12 * 0.95
   set in4_max   12 * 1.05

# Set Fan limits
   set fan1_min  3000
   set fan2_min  3000
   set fan3_min  3000
   set fan4_min  3000