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Table 63 Data Format of HDA Absolute Temperature History Table -1
Data table format version (=0002h)
Byte
Size
Field Name
Description
1:0
Word
Format
Version
3:2
Word
Sampling
Period
Absolute HDA Temperature sampling period in minutes.
0000h indicates sampling is disabled.
5:4
Word
Interval
Timer interval between entries in the history queue.
6
Byte
Max Op Limit
Maximum recommended continuous operating temperature. This is a one
byte 2’s complement number that allows a range from -127°C to +127°C
to be specified. 80h is an invalid value. This is a fixed value.
7
Byte
Over Limit
Maximum temperature limit. This is a one byte 2’s complement number
that allows a range from -127°C to +127°C to be specified. 80h is an
invalid value. This is a fixed value.
8
Byte
Min Op Limit
Minimum recommended continuous operating limit. This is a one byte 2’s
complement number that allows a range from -127°C to +127°C to be
specified. 80h is an invalid value. This is a fixed value.
9
Byte
Under Limit
Minimum temperature limit. This is a one byte 2’s complement number
that allows a range from -127°C to +127°C to be specified. 80h is an
invalid value. This is a fixed value.
29:10
Byte[20]
Reserved
31:30
Word
Queue Size
Number of entry locations in history queue.
This value is 128.
33:32
Word
Queue Index
Last updated entry in queue. Queue Index is zero-based, so Queue Index
0000h is the first location in the buffer (at offset 34). The most recent
temperature entered in the buffer is at Queue Index + 34.
See Note 1 and Note 2.
Table 64 Data Format of HDA Absolute Temperature History Table -2
Description
Byte
Size
Field
Name
(Queue Size+33):34
Byte[Queue Size]
Queue
Buffer
This is a circular buffer of absolute HDA
Temperature values. These are one byte 2’s
complement numbers, which allow a range
from -127°C to +127°C to be specified. A
value of 80h indicates an initial value or a
discontinuity in temperature recording.
The Actual time between samples may vary
because commands may not be interrupted.
The sampling period is the minimum time
between samples. See Note 1.
If the host changes the logging interval using
the volatile option, the interval between
entries in the queue may change between
power cycles with no indication to the host.
511: (Queue Size +34)
Byte[512-Queue Size-34]
Reserved
1.
Note 1 – The Absolute HDA Temperature History is preserved across power cycles with the requirement that
when the drive powers up, a new entry is made in the history queue of 80h, an invalid absolute temperature value.
This way an application viewing the history can see the discontinuity in temperature result from the drive being
turned off.
Note 2 – When the Absolute HDA Temperature history is cleared, for new drives or after changing the Logging Interval,
the Queue Index shall be set to zero and the first queue location shall be set to the current Absolute HDA Temperature
value. All remaining queue locations are set to 80h.
100
Hard Disk Drive Specification