Description¶

The Standard Microsystems Corporation (SMSC) EMC2103 chipscontain up to 4 temperature sensors and a single fan controller.

Fan rotation speeds are reported in RPM (rotations per minute). An alarm istriggered if the rotation speed has dropped below a programmable limit. Fanreadings can be divided by a programmable divider (1, 2, 4 or 8) to givethe readings more range or accuracy. Not all RPM values can accurately berepresented, so some rounding is done. With a divider of 1, the lowestrepresentable value is 480 RPM.

This driver supports RPM based control, to use this a fan targetshould be written to fan1_target and pwm1_enable should be set to 3.

The 2103-2 and 2103-4 variants have a third temperature sensor, which canbe connected to two anti-parallel diodes. These values can be readas temp3 and temp4. If only one diode is attached to this channel, temp4will show as “fault”. The module parameter “apd=0” can be used to suppressthis 4th channel when anti-parallel diodes are not fitted.