| 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_cmd | |
| 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 |