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fand - a fan controlling daemon
===============================

RUNNING
=======

Run, as root:
# fand /path/to/your/config.conf


CONFIGURATION
=============

Configuration files are using a simple yet powerful
LISP-like syntax which allows sensor values to be
manipulated in many ways.

Below a small example of what a configuration file
may look like when controlling only the CPU fan.


  (sensor "cputemp" (hwmon-sensor "hwmon1" "temp1_input"))
  
  (fan "cpufan" (hwmon-pwm "hwmon2" "pwm1"))

  (output "cpufan"
    (maximum
      (panic "45" "50" (sensor-input "cputemp"))
      (smooth "10"
        (steps
          (step "30" "0.00")
          (step "45" "0.65")
          (sensor-input "cputemp")))))


Sensor readings are given in celsius (as opposed
to milli celsius in sysfs), and fan speeds are
given as a floating-point number between 0 and 1.

Sensors and fans are named. Sensors can be used
as inputs multiple times using the 'sensor-input'
tag, whereas fans should only be used once.

In order to test your configuration prior to actually
applying it, you can choose to display fan speeds -
again, given as a floating point number between 0 and
1 - on the console. To do that, modify the fan entry:

  (fan "cpufan" (console-fan "PWM 1"))

where "PWM 1" is the display name of that fan.

The 'output' tag links an input to a fan, meaning that
this is what will actually control fan speeds. The first
argument is a named fan, 'cpufan' in our example, whereas
the second argument is an input sequence that produces a
number. Numbers outside the range [0..1] will be cut off.

There are the following input sources and modifiers:

  - (sensor-input "sensor")
      Reads the value of a named temperature sensor,
      in degrees celsius.
  - (steps (step "a1" "b1") (step "a2" "b2") ... (input))
      Maps an input to a different range, preferably the
      [0..1] range. If the number produced by the given
      input is between a1 and b2, the resulting value will
      be between b1 and b2.
  - (smooth "n" (input))
      Makes the resulting fan curve smooth by computing the
      average of the previous "n" values.
  - (panic "target" "critical" (input))
      Returns 1.0 (full fan speed) when the input temperature
      exceeds the "critical" temperature, and 0.0 (fan off)
      when it drops below the "target" temperature. Most useful
      in combination with (maximum).
  - (maximum (input1) (input2) ...)
      Computes the maximum value of all the inputs given.
  - (cutoff "off-below" "start-above" "start-value" (input))
      Turns the fans off when the input temperature drops
      below the "off-below" value, and starts them when
      it rises above the "start-above" value. "start-value"
      is the fan speed used to start the fans, which might
      have to be much higher than the minimum rotation speed.

Below another full configuration example:


  (sensor "gpu"  (hwmon-sensor "hwmon0" "temp1_input"))
  (sensor "cpu"  (hwmon-sensor "hwmon1" "temp1_input"))
  (sensor "sock" (hwmon-sensor "hwmon2" "temp1_input"))
  (sensor "case" (hwmon-sensor "hwmon2" "temp2_input"))

  (fan "cpu"  (hwmon-pwm "hwmon2" "pwm1"))
  (fan "case" (hwmon-pwm "hwmon2" "pwm3"))

  (output "cpu"
    (maximum
      (panic "60" "65" (sensor-input "cpu"))
      (smooth "7"
        (steps
          (step "45" "0.00")
          (step "60" "0.65")
          (sensor-input "cpu")))))

  (output "case"
    (cutoff "0.19" "0.25" "0.4"
      (maximum
        (panic "80" "82" (sensor-input "gpu"))
        (panic "48" "52" (sensor-input "case"))
        (panic "65" "70" (sensor-input "sock"))
        (smooth "10"
          (maximum
            (steps
              (step "50" "0.00")
              (step "50" "0.19")
              (step "55" "0.25")
              (step "80" "0.75")
              (sensor-input "gpu"))
            (steps
              (step "38" "0.00")
              (step "38" "0.19")
              (step "40" "0.25")
              (step "48" "0.60")
              (step "50" "0.75")
              (sensor-input "case"))
            (steps
              (step "40" "0.19")
              (step "50" "0.25")
              (step "65" "0.75")
              (sensor-input "sock")))))))