What: /sys/bus/w1/devices/.../alarms
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Date: May 2020
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Contact: Akira Shimahara <akira215corp@gmail.com>
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Description:
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(RW) 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
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(typical -55 degC to 125 degC), if not values will be trimmed
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to device min/max capabilities. Values are integer as they are
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stored in a 8bit register in the device. Lowest value is
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automatically put to TL. Once set, alarms could be search at
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master level, refer to Documentation/w1/w1-generic.rst for
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detailed information
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Users: any user space application which wants to communicate with
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w1_term device
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What: /sys/bus/w1/devices/.../eeprom
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Date: May 2020
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Contact: Akira Shimahara <akira215corp@gmail.com>
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Description:
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(WO) writing that file will either trigger a save of the
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device data to its embedded EEPROM, either restore data
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embedded in device EEPROM. Be aware that devices support
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limited EEPROM writing cycles (typical 50k)
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* 'save': save device RAM to EEPROM
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* 'restore': restore EEPROM data in device RAM
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Users: any user space application which wants to communicate with
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w1_term device
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What: /sys/bus/w1/devices/.../ext_power
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Date: May 2020
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Contact: Akira Shimahara <akira215corp@gmail.com>
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Description:
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(RO) return the power status by asking the device
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* '0': device parasite powered
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* '1': device externally powered
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* '-xx': xx is kernel error when reading power status
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Users: any user space application which wants to communicate with
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w1_term device
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What: /sys/bus/w1/devices/.../resolution
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Date: May 2020
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Contact: Akira Shimahara <akira215corp@gmail.com>
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Description:
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(RW) get or set the device resolution (on supported devices,
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if not, this entry is not present). Note that the resolution
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will be changed only in device RAM, so it will be cleared when
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power is lost. Trigger a 'save' to EEPROM command to keep
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values after power-on. Read or write are :
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* '9..14': device resolution in bit
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or resolution to set in bit
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* '-xx': xx is kernel error when reading the resolution
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* Anything else: do nothing
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Some DS18B20 clones are fixed in 12-bit resolution, so the
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actual resolution is read back from the chip and verified. Error
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is reported if the results differ.
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Users: any user space application which wants to communicate with
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w1_term device
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What: /sys/bus/w1/devices/.../temperature
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Date: May 2020
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Contact: Akira Shimahara <akira215corp@gmail.com>
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Description:
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(RO) return the temperature in 1/1000 degC.
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* If a bulk read has been triggered, it will directly
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return the temperature computed when the bulk read
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occurred, if available. If not yet available, nothing
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is returned (a debug kernel message is sent), you
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should retry later on.
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* If no bulk read has been triggered, it will trigger
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a conversion and send the result. Note that the
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conversion duration depend on the resolution (if
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device support this feature). It takes 94ms in 9bits
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resolution, 750ms for 12bits.
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Users: any user space application which wants to communicate with
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w1_term device
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What: /sys/bus/w1/devices/.../w1_slave
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Date: May 2020
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Contact: Akira Shimahara <akira215corp@gmail.com>
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Description:
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(RW) return the temperature in 1/1000 degC.
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*read*: return 2 lines with the hexa output data sent on the
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bus, return the CRC check and temperature in 1/1000 degC
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*write*:
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* '0' : save the 2 or 3 bytes to the device EEPROM
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(i.e. TH, TL and config register)
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* '9..14' : set the device resolution in RAM
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(if supported)
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* Anything else: do nothing
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refer to Documentation/w1/slaves/w1_therm.rst for detailed
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information.
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Users: any user space application which wants to communicate with
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w1_term device
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What: /sys/bus/w1/devices/w1_bus_masterXX/therm_bulk_read
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Date: May 2020
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Contact: Akira Shimahara <akira215corp@gmail.com>
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Description:
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(RW) trigger a bulk read conversion. read the status
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*read*:
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* '-1':
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conversion in progress on at least 1 sensor
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* '1' :
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conversion complete but at least one sensor
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value has not been read yet
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* '0' :
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no bulk operation. Reading temperature will
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trigger a conversion on each device
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*write*:
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'trigger': trigger a bulk read on all supporting
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devices on the bus
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Note that if a bulk read is sent but one sensor is not read
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immediately, the next access to temperature on this device
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will return the temperature measured at the time of issue
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of the bulk read command (not the current temperature).
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Users: any user space application which wants to communicate with
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w1_term device
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What: /sys/bus/w1/devices/.../conv_time
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Date: July 2020
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Contact: Ivan Zaentsev <ivan.zaentsev@wirenboard.ru>
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Description:
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(RW) Get, set, or measure a temperature conversion time. The
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setting remains active until a resolution change. Then it is
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reset to default (datasheet) conversion time for a new
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resolution.
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*read*:
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Actual conversion time in milliseconds.
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*write*:
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* '0':
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Set the default conversion time from the datasheet.
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* '1':
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Measure and set the conversion time. Make a single
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temperature conversion, measure an actual value.
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Increase it by 20% for temperature range. A new
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conversion time can be obtained by reading this
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same attribute.
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* other positive value:
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Set the conversion time in milliseconds.
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Users: An application using the w1_term device
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What: /sys/bus/w1/devices/.../features
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Date: July 2020
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Contact: Ivan Zaentsev <ivan.zaentsev@wirenboard.ru>
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Description:
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(RW) Control optional driver settings.
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Bit masks to read/write (bitwise OR):
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== ============================================================
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1 Enable check for conversion success. If byte 6 of
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scratchpad memory is 0xC after conversion, and
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temperature reads 85.00 (powerup value) or 127.94
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(insufficient power) - return a conversion error.
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2 Enable poll for conversion completion. Generate read cycles
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after the conversion start and wait for 1's. In parasite
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power mode this feature is not available.
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== ============================================================
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*read*:
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Currently selected features.
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*write*:
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Select features.
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Users: An application using the w1_term device
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