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hwmon: (ds1621) Update documentation

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Replace some written information with tables to improve readability
and to simplify adding newer devices in the future.

Signed-off-by: Robert Coulson <rob.coulson@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Robert Coulson 2013-06-10 18:46:03 -07:00 committed by Guenter Roeck
parent 260f81ffc1
commit 87438c2c54
1 changed files with 44 additions and 24 deletions
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@ -73,37 +73,57 @@ any of the limits have ever been met or exceeded since last power-up or
reset. Be aware: When testing, it showed that the status of Tout can change
with neither of the alarms set.
Temperature conversion of the DS1621 takes up to 1000ms; internal access to
non-volatile registers may last for 10ms or below.
Since there is no version or vendor identification register, there is
no unique identification for these devices. Therefore, explicit device
instantiation is required for correct device identification and functionality
(one device per address in this address range: 0x48..0x4f).
The DS1625 is pin compatible and functionally equivalent with the DS1621,
but the DS1621 is meant to replace it. The DS1631, DS1721, and DS1731 are
also pin compatible with the DS1621, but provide multi-resolution support.
also pin compatible with the DS1621 and provide multi-resolution support.
Since there is no version or vendor identification register, there is
no unique identification for these devices. Therefore, explicit device
instantiation is required for correct device identification and functionality.
Additionally, the DS1721 data sheet says the temperature flags (THF and TLF)
are used internally, however, these flags do get set and cleared as the actual
temperature crosses the min or max settings (which by default are set to 75
and 80 degrees respectively).
And, for correct identification and operation, each device must be
explicitly instantiated, one device per address, in this address
range: 0x48..0x4f.
Temperature Conversion:
-----------------------
DS1621 - 750ms (older devices may take up to 1000ms)
DS1625 - 500ms
DS1631 - 93ms..750ms for 9..12 bits resolution, respectively.
DS1721 - 93ms..750ms for 9..12 bits resolution, respectively.
DS1731 - 93ms..750ms for 9..12 bits resolution, respectively.
The DS1721 is pin compatible with the DS1621, has an accuracy of +/- 1.0
degree Celsius (from -10 to +85 degrees), a minimum/maximum alarm default
setting of 75 and 80 degrees, and a maximum conversion time of 750ms.
Note:
On the DS1621, internal access to non-volatile registers may last for 10ms
or less (unverified on the other devices).
In addition, the DS1721 supports four resolution settings from 9 to 12 bits
(defined in degrees C per LSB: 0.5, 0.25, 0.125, and 0.0625, respectively),
that are set at device power on to the highest resolution: 12-bits.
Temperature Accuracy:
---------------------
DS1621: +/- 0.5 degree Celsius (from 0 to +70 degrees)
DS1625: +/- 0.5 degree Celsius (from 0 to +70 degrees)
DS1631: +/- 0.5 degree Celsius (from 0 to +70 degrees)
DS1721: +/- 1.0 degree Celsius (from -10 to +85 degrees)
DS1731: +/- 1.0 degree Celsius (from -10 to +85 degrees)
One additional note about the ds1721 is that although the data sheet says
the temperature flags (THF and TLF) are used internally, these flags do
get set and cleared as the actual temperature crosses the min or max settings.
Note:
Please refer to the device datasheets for accuracy at other temperatures.
The DS1631 and DS1731 are pin compatible with the DS1621 and feature compatible
with the DS1721. However, the DS1631 accuracy is +/- 0.5 degree Celsius (from 0
to +70 degrees), while the DS1731 accuracy is +/-1 degree Celsius (from -10 to
+85 degrees).
Temperature Resolution:
-----------------------
As mentioned above, the DS1631, DS1721, and DS1731 provide multi-resolution
support, which is achieved via the R0 and R1 config register bits, where:
R0..R1
------
0 0 => 9 bits, 0.5 degrees Celcius
1 0 => 10 bits, 0.25 degrees Celcius
0 1 => 11 bits, 0.125 degrees Celcius
1 1 => 12 bits, 0.0625 degrees Celcius
Note:
At initial device power-on, the default resolution is set to 12-bits.
The resolution mode for the DS1631, DS1721, or DS1731 can be changed from
userspace, via the device 'update_interval' sysfs attribute. This attribute
@ -112,12 +132,12 @@ values defined in the datasheet as follows:
Resolution Conversion Time Input Range
(C/LSB) (msec) (msec)
--------------------------------------------
------------------------------------------------
0.5 93.75 0....94
0.25 187.5 95...187
0.125 375 188..375
0.0625 750 376..infinity
--------------------------------------
------------------------------------------------
The following examples show how the 'update_interval' attribute can be
used to change the conversion time: