Run, as root:
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")))))
In this config, hwmon-sensor and hwmon-pwm refer
to files in /sys/class/hwmon. However, on modern
systems, these are often USB-based, and can move
around significantly. Consider using the following
command to use a friendlier label in your config
files:
cat /sys/class/hwmon/hwmon*/name | nl -v 0
The previous example might look like this if you made that choice with an AMD cpu:
(sensor "cputemp" (hwmon-sensor "k10temp" "temp1_input"))
(fan "cpufan" (hwmon-pwm "it8792" "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")))))))