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 26 * 'save': save device RAM to EEPROM 27 * 'restore': restore EEPROM data in device RAM 28 29Users: any user space application which wants to communicate with 30 w1_term device 31 32 33What: /sys/bus/w1/devices/.../ext_power 34Date: May 2020 35Contact: Akira Shimahara <akira215corp@gmail.com> 36Description: 37 (RO) return the power status by asking the device 38 39 * '0': device parasite powered 40 * '1': device externally powered 41 * '-xx': xx is kernel error when reading power status 42 43Users: any user space application which wants to communicate with 44 w1_term device 45 46 47What: /sys/bus/w1/devices/.../resolution 48Date: May 2020 49Contact: Akira Shimahara <akira215corp@gmail.com> 50Description: 51 (RW) get or set the device resolution (on supported devices, 52 if not, this entry is not present). Note that the resolution 53 will be changed only in device RAM, so it will be cleared when 54 power is lost. Trigger a 'save' to EEPROM command to keep 55 values after power-on. Read or write are : 56 57 * '9..14': device resolution in bit 58 or resolution to set in bit 59 * '-xx': xx is kernel error when reading the resolution 60 * Anything else: do nothing 61 62 Some DS18B20 clones are fixed in 12-bit resolution, so the 63 actual resolution is read back from the chip and verified. Error 64 is reported if the results differ. 65Users: any user space application which wants to communicate with 66 w1_term device 67 68 69What: /sys/bus/w1/devices/.../temperature 70Date: May 2020 71Contact: Akira Shimahara <akira215corp@gmail.com> 72Description: 73 (RO) return the temperature in 1/1000 degC. 74 75 * If a bulk read has been triggered, it will directly 76 return the temperature computed when the bulk read 77 occurred, if available. If not yet available, nothing 78 is returned (a debug kernel message is sent), you 79 should retry later on. 80 * If no bulk read has been triggered, it will trigger 81 a conversion and send the result. Note that the 82 conversion duration depend on the resolution (if 83 device support this feature). It takes 94ms in 9bits 84 resolution, 750ms for 12bits. 85 86Users: any user space application which wants to communicate with 87 w1_term device 88 89 90What: /sys/bus/w1/devices/.../w1_slave 91Date: May 2020 92Contact: Akira Shimahara <akira215corp@gmail.com> 93Description: 94 (RW) return the temperature in 1/1000 degC. 95 *read*: return 2 lines with the hexa output data sent on the 96 bus, return the CRC check and temperature in 1/1000 degC 97 *write*: 98 99 * '0' : save the 2 or 3 bytes to the device EEPROM 100 (i.e. TH, TL and config register) 101 * '9..14' : set the device resolution in RAM 102 (if supported) 103 * Anything else: do nothing 104 105 refer to Documentation/w1/slaves/w1_therm.rst for detailed 106 information. 107Users: any user space application which wants to communicate with 108 w1_term device 109 110 111What: /sys/bus/w1/devices/w1_bus_masterXX/therm_bulk_read 112Date: May 2020 113Contact: Akira Shimahara <akira215corp@gmail.com> 114Description: 115 (RW) trigger a bulk read conversion. read the status 116 117 *read*: 118 * '-1': 119 conversion in progress on at least 1 sensor 120 * '1' : 121 conversion complete but at least one sensor 122 value has not been read yet 123 * '0' : 124 no bulk operation. Reading temperature will 125 trigger a conversion on each device 126 127 *write*: 128 'trigger': trigger a bulk read on all supporting 129 devices on the bus 130 131 Note that if a bulk read is sent but one sensor is not read 132 immediately, the next access to temperature on this device 133 will return the temperature measured at the time of issue 134 of the bulk read command (not the current temperature). 135Users: any user space application which wants to communicate with 136 w1_term device 137 138 139What: /sys/bus/w1/devices/.../conv_time 140Date: July 2020 141Contact: Ivan Zaentsev <ivan.zaentsev@wirenboard.ru> 142Description: 143 (RW) Get, set, or measure a temperature conversion time. The 144 setting remains active until a resolution change. Then it is 145 reset to default (datasheet) conversion time for a new 146 resolution. 147 148 *read*: 149 Actual conversion time in milliseconds. 150 151 *write*: 152 * '0': 153 Set the default conversion time from the datasheet. 154 * '1': 155 Measure and set the conversion time. Make a single 156 temperature conversion, measure an actual value. 157 Increase it by 20% for temperature range. A new 158 conversion time can be obtained by reading this 159 same attribute. 160 * other positive value: 161 Set the conversion time in milliseconds. 162 163Users: An application using the w1_term device 164 165 166What: /sys/bus/w1/devices/.../features 167Date: July 2020 168Contact: Ivan Zaentsev <ivan.zaentsev@wirenboard.ru> 169Description: 170 (RW) Control optional driver settings. 171 Bit masks to read/write (bitwise OR): 172 173 == ============================================================ 174 1 Enable check for conversion success. If byte 6 of 175 scratchpad memory is 0xC after conversion, and 176 temperature reads 85.00 (powerup value) or 127.94 177 (insufficient power) - return a conversion error. 178 179 2 Enable poll for conversion completion. Generate read cycles 180 after the conversion start and wait for 1's. In parasite 181 power mode this feature is not available. 182 == ============================================================ 183 184 *read*: 185 Currently selected features. 186 187 *write*: 188 Select features. 189 190Users: An application using the w1_term device 191