@@ -27,75 +27,72 @@ W1_THERM_DS1825 0x3B
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W1_THERM_DS28EA00 0x42
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==================== ====
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- Support is provided through the sysfs w1_slave file . Each open and
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- read sequence will initiate a temperature conversion then provide two
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+ Support is provided through the sysfs entry `` w1_slave `` . Each open and
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+ read sequence will initiate a temperature conversion, then provide two
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lines of ASCII output. The first line contains the nine hex bytes
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read along with a calculated crc value and YES or NO if it matched.
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If the crc matched the returned values are retained. The second line
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displays the retained values along with a temperature in millidegrees
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Centigrade after t=.
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- Alternatively, temperature can be read using temperature sysfs, it
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- return only temperature in millidegrees Centigrade.
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+ Alternatively, temperature can be read using `` temperature `` sysfs, it
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+ returns only the temperature in millidegrees Centigrade.
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- A bulk read of all devices on the bus could be done writing ' trigger'
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- in the therm_bulk_read sysfs entry at w1_bus_master level. This will
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- sent the convert command on all devices on the bus, and if parasite
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- powered devices are detected on the bus (and strong pullup is enable
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+ A bulk read of all devices on the bus could be done writing `` trigger ``
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+ to `` therm_bulk_read `` entry at w1_bus_master level. This will
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+ send the convert command to all devices on the bus, and if parasite
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+ powered devices are detected on the bus (and strong pullup is enabled
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in the module), it will drive the line high during the longer conversion
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time required by parasited powered device on the line. Reading
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- therm_bulk_read will return 0 if no bulk conversion pending,
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+ `` therm_bulk_read `` will return 0 if no bulk conversion pending,
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-1 if at least one sensor still in conversion, 1 if conversion is complete
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but at least one sensor value has not been read yet. Result temperature is
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- then accessed by reading the temperature sysfs entry of each device, which
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+ then accessed by reading the `` temperature `` entry of each device, which
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may return empty if conversion is still in progress. Note that if a bulk
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read is sent but one sensor is not read immediately, the next access to
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- temperature on this device will return the temperature measured at the
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+ `` temperature `` on this device will return the temperature measured at the
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time of issue of the bulk read command (not the current temperature).
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A strong pullup will be applied during the conversion if required.
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- ``conv_time `` sysfs entry is used to get current conversion time (read), and
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+ ``conv_time `` is used to get current conversion time (read), and
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adjust it (write). A temperature conversion time depends on the device type and
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it's current resolution. Default conversion time is set by the driver according
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to the device datasheet. A conversion time for many original device clones
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deviate from datasheet specs. There are three options: 1) manually set the
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correct conversion time by writing a value in milliseconds to ``conv_time ``; 2)
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auto measure and set a conversion time by writing ``1 `` to
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- ``conv_time ``; 3) use ``features `` entry to enable poll for conversion
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+ ``conv_time ``; 3) use ``features `` to enable poll for conversion
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completion. Options 2, 3 can't be used in parasite power mode. To get back to
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the default conversion time write ``0 `` to ``conv_time ``.
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- Writing a value between 9 and 12 to the sysfs w1_slave file will change the
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- precision of the sensor for the next readings. This value is in (volatile)
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- SRAM, so it is reset when the sensor gets power-cycled.
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+ Writing a resolution value (in bits) to `` w1_slave `` will change the
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+ precision of the sensor for the next readings. Allowed resolutions are defined by
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+ the sensor. Resolution is reset when the sensor gets power-cycled.
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- To store the current precision configuration into EEPROM, the value 0
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- has to be written to the sysfs w1_slave file. Since the EEPROM has a limited
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- amount of writes (>50k), this command should be used wisely.
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+ To store the current resolution in EEPROM, write `` 0 `` to `` w1_slave ``.
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+ Since the EEPROM has a limited amount of writes (>50k), this command should be
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+ used wisely.
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- Alternatively, resolution can be set or read (value from 9 to 12) using the
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- dedicated resolution sysfs entry on each device. This sysfs entry is not present
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- for devices not supporting this feature.
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+ Alternatively, resolution can be read or written using the dedicated
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+ ``resolution `` entry on each device, if supported by the sensor.
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- Some non-genuine DS18B20 chips are
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- fixed in 12-bit mode only, so the actual resolution is read back from the chip
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- and verified by the driver.
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+ Some non-genuine DS18B20 chips are fixed in 12-bit mode only, so the actual
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+ resolution is read back from the chip and verified.
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Note: Changing the resolution reverts the conversion time to default.
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- The write-only sysfs entry eeprom is an alternative for EEPROM operations:
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- * ' save': will save device RAM to EEPROM
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- * 'restore': will restore EEPROM data in device RAM.
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+ The write-only sysfs entry `` eeprom `` is an alternative for EEPROM operations.
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+ Write `` save `` to save device RAM to EEPROM. Write `` restore `` to restore EEPROM
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+ data in device RAM.
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- ext_power syfs entry allow tho check the power status of each device.
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- * '0': device parasite powered
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- * '1': device externally powered
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+ ``ext_power `` entry allows checking the power state of each device. Reads
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+ ``0 `` if the device is parasite powered, ``1 `` if the device is externally powered.
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- sysfs alarms allow read or write TH and TL (Temperature High an Low) alarms.
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+ Sysfs `` alarms `` allow read or write TH and TL (Temperature High an Low) alarms.
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Values shall be space separated and in the device range (typical -55 degC
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to 125 degC). Values are integer as they are store in a 8bit register in
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- the device. Lowest value is automatically put to TL.Once set, alarms could
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+ the device. Lowest value is automatically put to TL. Once set, alarms could
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be search at master level.
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The module parameter strong_pullup can be set to 0 to disable the
@@ -119,24 +116,24 @@ The DS28EA00 provides an additional two pins for implementing a sequence
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detection algorithm. This feature allows you to determine the physical
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location of the chip in the 1-wire bus without needing pre-existing
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knowledge of the bus ordering. Support is provided through the sysfs
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- w1_seq file. The file will contain a single line with an integer value
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+ `` w1_seq ``. The file will contain a single line with an integer value
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representing the device index in the bus starting at 0.
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``features `` sysfs entry controls optional driver settings per device.
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- Insufficient power in parasite mode, line noise and insufficient conversion time
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- may lead to conversion failure. Original DS18B20 and some clones allow for
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+ Insufficient power in parasite mode, line noise and insufficient conversion
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+ time may lead to conversion failure. Original DS18B20 and some clones allow for
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detection of invalid conversion. Write bit mask ``1 `` to ``features `` to enable
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checking the conversion success. If byte 6 of scratchpad memory is 0xC after
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conversion and temperature reads 85.00 (powerup value) or 127.94 (insufficient
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power), the driver returns a conversion error. Bit mask ``2 `` enables poll for
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conversion completion (normal power only) by generating read cycles on the bus
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after conversion starts. In parasite power mode this feature is not available.
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- Feature bit masks may be combined (OR). See accompanying sysfs documentation:
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- :ref: ` Documentation/w1/slaves/ w1_therm.rst < w1_therm >`
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+ Feature bit masks may be combined (OR). More details in
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+ Documentation/ABI/testing/sysfs-driver- w1_therm
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GX20MH01 device shares family number 0x28 with DS18*20. The device is generally
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- compatible with DS18B20. Added are lowest 2^-5 , 2^-6 temperature bits in Config
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- register; R2 bit in Config register enabling 13 and 14 bit resolutions. The
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- device is powered up in 14-bit resolution mode. The conversion times specified
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- in the datasheet are too low and have to be increased. The device supports
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- driver features ``1 `` and ``2 ``.
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+ compatible with DS18B20. Added are lowest 2\ :sup: `-5` , 2\ :sup: `-6` temperature
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+ bits in Config register; R2 bit in Config register enabling 13 and 14 bit
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+ resolutions. The device is powered up in 14-bit resolution mode. The conversion
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+ times specified in the datasheet are too low and have to be increased. The
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+ device supports driver features ``1 `` and ``2 ``.
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