| What: /sys/bus/w1/devices/.../alarms |
| Date: May 2020 |
| Contact: Akira Shimahara <akira215corp@gmail.com> |
| 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 |
| Date: May 2020 |
| Contact: Akira Shimahara <akira215corp@gmail.com> |
| 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 <akira215corp@gmail.com> |
| 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 <akira215corp@gmail.com> |
| 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 <akira215corp@gmail.com> |
| 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 <akira215corp@gmail.com> |
| 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 <akira215corp@gmail.com> |
| 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 <ivan.zaentsev@wirenboard.ru> |
| 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 <ivan.zaentsev@wirenboard.ru> |
| 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 |
