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