|
@@ -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.
|
|
|
-
|
|
|
-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.
|
|
|
-
|
|
|
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.
|
|
|
-
|
|
|
-And, for correct identification and operation, each device must be
|
|
|
-explicitly instantiated, one device per address, in this address
|
|
|
-range: 0x48..0x4f.
|
|
|
+instantiation is required for correct device identification and functionality
|
|
|
+(one device per address in this address range: 0x48..0x4f).
|
|
|
|
|
|
-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.
|
|
|
-
|
|
|
-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.
|
|
|
-
|
|
|
-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.
|
|
|
-
|
|
|
-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).
|
|
|
+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 and provide multi-resolution support.
|
|
|
+
|
|
|
+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).
|
|
|
+
|
|
|
+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.
|
|
|
+
|
|
|
+Note:
|
|
|
+On the DS1621, internal access to non-volatile registers may last for 10ms
|
|
|
+or less (unverified on the other devices).
|
|
|
+
|
|
|
+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)
|
|
|
+
|
|
|
+Note:
|
|
|
+Please refer to the device datasheets for accuracy at other temperatures.
|
|
|
+
|
|
|
+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:
|