Description¶

The National Semiconductor Super I/O chip includes complete hardwaremonitoring capabilities. It can monitor up to 18 voltages, 8 fans and6 temperature sensors. Only the fans and temperatures are supported atthe moment, voltages aren’t.

This chip also has fan controlling features (up to 4 PWM outputs),which are partly supported by this driver.

The driver assumes that no more than one chip is present, which seemsreasonable.

Fan Monitoring¶

Fan rotation speeds are reported as 14-bit values from a gated clocksignal. Speeds down to 83 RPM can be measured.

An alarm is triggered if the rotation speed drops below a programmablelimit. Another alarm is triggered if the speed is too low to be measured(including stalled or missing fan).

Fan Speed Control¶

Fan speed can be controlled by PWM outputs. There are 4 possible modes:always off, always on, manual and automatic. The latter isn’t supportedby the driver: you can only return to that mode if it was the originalsetting, and the configuration interface is missing.

Temperature Monitoring¶

The PC87427 relies on external sensors (following the SensorPathstandard), so the resolution and range depend on the type of sensorconnected. The integer part can be 8-bit or 9-bit, and can be signed ornot. I couldn’t find a way to figure out the external sensor datatemperature format, so user-space adjustment (typically by a factor 2)may be required.