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hwmon: (ds1621) Add ds1631 chip support to ds1621 driver and documentation

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Add definitions, information, and code for ds1631 chip support
to the ds1621 driver.

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
2013-05-16 15:10:41 -07:00
committed by Guenter Roeck
parent 3a8fe33155
commit 79c1cc1c90
3 changed files with 45 additions and 10 deletions
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27
Documentation/hwmon/ds1621
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@@ -14,6 +14,11 @@ Supported chips:
Addresses scanned: I2C 0x48 - 0x4f
Datasheet: Publicly available from www.datasheetarchive.com
* Maxim Integrated DS1631
Prefix: 'ds1631'
Addresses scanned: I2C 0x48 - 0x4f
Datasheet: Publicly available from www.maximintegrated.com
* Maxim Integrated DS1721
Prefix: 'ds1721'
Addresses scanned: I2C 0x48 - 0x4f
@@ -69,7 +74,15 @@ 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.
but the DS1621 is meant to replace it. The DS1631 and DS1721 are also
pin compatible with the DS1621, but provide multi-resolution support.
Since there is no version register, there is no unique identification
for these devices. In addition, the DS1631 and DS1721 will emulate a
DS1621 device, if not explicitly instantiated (why? because the detect
function compares the temperature register values bits and checks for a
9-bit resolution). Therefore, for correct device identification and
functionality, explicit device instantiation is required.
The DS1721 is pin compatible with the DS1621, has an accuracy of +/- 1.0
degree Celsius over a -10 to +85 degree range, a minimum/maximum alarm
@@ -78,9 +91,17 @@ 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, respectifully),
that are set at device power on to the highest resolution: 12-bits (0.0625 degree C).
that are set at device power on to the highest resolution: 12-bits.
Changing the DS1721 resolution mode affects the conversion time and can be
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 is also pin compatible with the DS1621 and feature compatible with
the DS1721, however the DS1631 accuracy is +/- 0.5 degree Celsius over the
same range.
Changing the DS1631/1721 resolution mode affects the conversion time and can be
done from userspace, via the device 'update_interval' sysfs attribute. This
attribute will normalize range of input values to the device maximum resolution
values defined in the datasheet as such: