1What: /sys/bus/w1/devices/.../alarms 2Date: May 2020 3Contact: Akira Shimahara <akira215corp@gmail.com> 4Description: 5 (RW) read or write TH and TL (Temperature High an Low) alarms. 6 Values shall be space separated and in the device range 7 (typical -55 degC to 125 degC), if not values will be trimmed 8 to device min/max capabilities. Values are integer as they are 9 stored in a 8bit register in the device. Lowest value is 10 automatically put to TL. Once set, alarms could be search at 11 master level, refer to Documentation/w1/w1-generic.rst for 12 detailed information 13Users: any user space application which wants to communicate with 14 w1_term device 15 16 17What: /sys/bus/w1/devices/.../eeprom 18Date: May 2020 19Contact: Akira Shimahara <akira215corp@gmail.com> 20Description: 21 (WO) writing that file will either trigger a save of the 22 device data to its embedded EEPROM, either restore data 23 embedded in device EEPROM. Be aware that devices support 24 limited EEPROM writing cycles (typical 50k) 25 * 'save': save device RAM to EEPROM 26 * 'restore': restore EEPROM data in device RAM 27Users: any user space application which wants to communicate with 28 w1_term device 29 30 31What: /sys/bus/w1/devices/.../ext_power 32Date: May 2020 33Contact: Akira Shimahara <akira215corp@gmail.com> 34Description: 35 (RO) return the power status by asking the device 36 * '0': device parasite powered 37 * '1': device externally powered 38 * '-xx': xx is kernel error when reading power status 39Users: any user space application which wants to communicate with 40 w1_term device 41 42 43What: /sys/bus/w1/devices/.../resolution 44Date: May 2020 45Contact: Akira Shimahara <akira215corp@gmail.com> 46Description: 47 (RW) get or set the device resolution (on supported devices, 48 if not, this entry is not present). Note that the resolution 49 will be changed only in device RAM, so it will be cleared when 50 power is lost. Trigger a 'save' to EEPROM command to keep 51 values after power-on. Read or write are : 52 * '9..14': device resolution in bit 53 or resolution to set in bit 54 * '-xx': xx is kernel error when reading the resolution 55 * Anything else: do nothing 56 Some DS18B20 clones are fixed in 12-bit resolution, so the 57 actual resolution is read back from the chip and verified. Error 58 is reported if the results differ. 59Users: any user space application which wants to communicate with 60 w1_term device 61 62 63What: /sys/bus/w1/devices/.../temperature 64Date: May 2020 65Contact: Akira Shimahara <akira215corp@gmail.com> 66Description: 67 (RO) return the temperature in 1/1000 degC. 68 * If a bulk read has been triggered, it will directly 69 return the temperature computed when the bulk read 70 occurred, if available. If not yet available, nothing 71 is returned (a debug kernel message is sent), you 72 should retry later on. 73 * If no bulk read has been triggered, it will trigger 74 a conversion and send the result. Note that the 75 conversion duration depend on the resolution (if 76 device support this feature). It takes 94ms in 9bits 77 resolution, 750ms for 12bits. 78Users: any user space application which wants to communicate with 79 w1_term device 80 81 82What: /sys/bus/w1/devices/.../w1_slave 83Date: May 2020 84Contact: Akira Shimahara <akira215corp@gmail.com> 85Description: 86 (RW) return the temperature in 1/1000 degC. 87 *read*: return 2 lines with the hexa output data sent on the 88 bus, return the CRC check and temperature in 1/1000 degC 89 *write* : 90 * '0' : save the 2 or 3 bytes to the device EEPROM 91 (i.e. TH, TL and config register) 92 * '9..14' : set the device resolution in RAM 93 (if supported) 94 * Anything else: do nothing 95 refer to Documentation/w1/slaves/w1_therm.rst for detailed 96 information. 97Users: any user space application which wants to communicate with 98 w1_term device 99 100 101What: /sys/bus/w1/devices/w1_bus_masterXX/therm_bulk_read 102Date: May 2020 103Contact: Akira Shimahara <akira215corp@gmail.com> 104Description: 105 (RW) trigger a bulk read conversion. read the status 106 *read*: 107 * '-1': conversion in progress on at least 1 sensor 108 * '1' : conversion complete but at least one sensor 109 value has not been read yet 110 * '0' : no bulk operation. Reading temperature will 111 trigger a conversion on each device 112 *write*: 'trigger': trigger a bulk read on all supporting 113 devices on the bus 114 Note that if a bulk read is sent but one sensor is not read 115 immediately, the next access to temperature on this device 116 will return the temperature measured at the time of issue 117 of the bulk read command (not the current temperature). 118Users: any user space application which wants to communicate with 119 w1_term device 120 121 122What: /sys/bus/w1/devices/.../conv_time 123Date: July 2020 124Contact: Ivan Zaentsev <ivan.zaentsev@wirenboard.ru> 125Description: 126 (RW) Get, set, or measure a temperature conversion time. The 127 setting remains active until a resolution change. Then it is 128 reset to default (datasheet) conversion time for a new 129 resolution. 130 131 *read*: Actual conversion time in milliseconds. *write*: 132 '0': Set the default conversion time from the datasheet. 133 '1': Measure and set the conversion time. Make a single 134 temperature conversion, measure an actual value. 135 Increase it by 20% for temperature range. A new 136 conversion time can be obtained by reading this 137 same attribute. 138 other positive value: 139 Set the conversion time in milliseconds. 140 141Users: An application using the w1_term device 142 143 144What: /sys/bus/w1/devices/.../features 145Date: July 2020 146Contact: Ivan Zaentsev <ivan.zaentsev@wirenboard.ru> 147Description: 148 (RW) Control optional driver settings. 149 Bit masks to read/write (bitwise OR): 150 151 1: Enable check for conversion success. If byte 6 of 152 scratchpad memory is 0xC after conversion, and 153 temperature reads 85.00 (powerup value) or 127.94 154 (insufficient power) - return a conversion error. 155 156 2: Enable poll for conversion completion. Generate read cycles 157 after the conversion start and wait for 1's. In parasite 158 power mode this feature is not available. 159 160 *read*: Currently selected features. 161 *write*: Select features. 162 163Users: An application using the w1_term device 164