Advanced Configuration and Power Interface Specification

Power Source and Power Meter Devices
0x00000003 – Failure to set trip points due to unknown hardware error
0x00000004 – 0xFFFFFFFF - Reserved
10.4.3 _PMM (Power Meter Measurement)
This object returns the latest measurement reading from the power meter device. The value returned
represents real power (i.e. power factor is included in the value). In most cases this is a rolling
average value that is computed by the firmware over an averaging interval. On systems where this
interval can be configured, the _PAI object should be present under the power meter device (see
Section 10.4.4).
Arguments:
None
Return Value:
An Integer is returned to represent the latest measurement reading from the power meter device.
This value should be in the unit specified in the power meter capabilities (typically in milliwatts),
and is required to be the RMS value if the power meter is measuring in AC. If an error occurs while
obtaining the meter reading or if the value is not available then an Integer with all bits set is returned.
10.4.4 _PAI (Power Averaging Interval)
This object sets the averaging interval used by the power meter. The averaging interval is the total
time the power meter will take instantaneous measurement samples for, before averaging them to
produce the average power measurement as returned by _PMM. If the platform changes the
averaging interval independently from OSPM, the platform must issue a Notify(power_meter, 0x84)
to indicate the change to the OSPM. Upon receiving the notification, OSPM evaluates the _GAI
object to read the new averaging interval.
Arguments: (1)
Arg0 – An Integer that represents the desired value OSPM chose to be the power averaging interval,
in milliseconds. This value needs to be within the minimum and maximum averaging interval as
specified by _PMC. Otherwise, a failure result code is returned.
Return Value:
An Integer containing the status of the operation:
0x00000000 – Success
0x00000001 – Failure to set power averaging interval because it is out of range
0x00000002 – Failure to set power averaging interval due to hardware timeout
0x00000003 – Failure to set power averaging interval due to unknown hardware error
0x00000004 – 0xFFFFFFFF - Reserved
10.4.5 _GAI (Get Averaging Interval)
This object gets the averaging interval used by the power meter. The averaging interval is the total
time the power meter will take instantaneous measurement samples for, before averaging them to
produce the average power measurement as returned by _PMM. If the platform changes the
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