These chips support up to fourteen sensors. Not all of the following sensors are supported on all chips.
Sensor | Units | Typical Use | |||||||||||||||||||||||||||||||||||||||||||||
l_temp |
Each temperature and voltage sensor has a programmable high- and low-limit; fan sensors have only a low-limit. The user can set the threshold values using sysctl(8)
hw.dbcool0.l_temp.low_lim = 35 degrees C
hw.dbcool0.l_temp.hi_lim = 75 degrees C
hw.dbcool0.fan1.low_lim = 300 RPM
hw.dbcool0.Vcc.low_lim = 2250 milliVolts
hw.dbcool0.Vcc.hi_lim = 2750 milliVolts
Temperature sensors also have Tmin, Trange, Thyst, and Ttherm sysctl(8) variables; these values are used by the fan speed controllers.
All sysctl(8) variables associated with temperature sensors are in units of degC, since this is the unit which is programmed into the device registers. Limit values for voltage sensors are in millivolts. The low limit value for fan sensors is measured in RPM; due to the manner in which fan speed is measured, the lowest possible value for a fan limit is 83 RPM.
All members of the dbCool family support Pulse-Width Modulated (PWM) fan speed control based on temperature thresholds - the fan will spin up when one or more thermal sensors exceeds its configured Tmin value. The fan will go faster as the temperature rises, and will slow down as the temperature falls. If the temperature exceeds the sensor's Ttherm value, the THERM signal will be asserted, and if enabled the fan will run at full speed. The fan will be turned off when the sensor(s) that triggered it reports a temperature which is at least Thyst degrees below its Tmin threshold.
Each fan controller is programmable using the following sysctl(8) variables.
hw.dbcool0.fan_ctl_0.behavior
hw.dbcool0.fan_ctl_0.min_duty
hw.dbcool0.fan_ctl_0.max_duty
hw.dbcool0.fan_ctl_0.cur_duty
The behavior variable controls the selection of temperature sensors associated with the fan controller. When the associated temperature sensor reaches its Tmin value, the fan controller starts the fan at its minimum duty cycle; when the associated temperature sensor reaches its Ttherm value and asserts the THERM signal (or if an external THERM signal is asserted), the fan controller sets the fan speed to a 100% duty cycle. Between these two settings, each temperature sensor is used to calculate a duty cycle linearly based on the slope defined by the temperature sensor's range variable. When the associated temperature falls at least Thyst degress below its Tmin value, the fan controller will turn off the fan. (On the ADM1030, the value for Thyst is fixed at 5 degrees C.)
Valid values for the behavior variable are:
local (not available on ADM1030)
remote1
remote2 (not available on ADM1030)
local+remote2 (not available on ADM1030)
all-temps
full-speed (not available on ADM1030)
manual
disabled
When the behavior variable is set to ``manual'', the cur-duty variable becomes user-writeable and can be set to any value between 0 and 100 inclusive to control the fan's duty cycle manually. In all other behavior modes, the cur-duty variable is read-only and updates are ignored.
The min-duty and max-duty variables define the range over which the fan controller will manage the fan's duty cycle. On the ADM1030, these values are not separately controllable. The max-duty is fixed at 100%, and the cur-duty variable is used to specify the minimum duty cycle when the fan controller is running in automatic mode.
Note that the duty-cycle value does not directly correspond to the fan's speed. That is, a 33% duty cycle does not mean that the fan runs at 33% of its maximum speed; in actuality, a 33% duty cycle drives the fan at a speed close to 50% of its maximum. Fan speed correlates approximately to the square root of the duty cycle.
Current CritMax CritMin CritCap Unit
l_temp: 44.250 degC
r1_temp: 41.250 degC
r2_temp: N/A
Vccp: 0.002 V
Vcc: 3.351 V
fan1: N/A
fan2: N/A
fan3: N/A
fan4: N/A
Using this information, the following commands in
/etc/envsys.conf
will set appropriate limits for CPU temperature and chip supply
voltage, and powerd will be notified if the limits are exceeded:
dbcool0 {
sensor1 {
warning-max = 60C;
critical-max = 65C;
}
sensor4 {
critical-min = 3.1;
warning-min = 3.2;
critical-max = 3.5;
}
}
Alternatively, set the following commands in
/etc/sysctl.conf
to perform limit checking in the hardware:
hw.dbcool0.r1_temp.hi_lim = 65
hw.dbcool0.Vcc.low_lim = 3200000
hw.dbcool0.Vcc.hi_lim = 3500000
The ADT7466 chip, although officially a member of the dbCool family, is programmed quite differently. The fan controllers on this chip are not currently implemented.
The PECI (Processor Environment Control Interface) temperature sensors and the associated PWM behavior modes on the ADT7490 are not currently supported.