1 What: /sys/bus/w1/devices/.../alarms
3 Contact: Akira Shimahara <akira215corp@gmail.com>
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
13 Users: any user space application which wants to communicate with
17 What: /sys/bus/w1/devices/.../eeprom
19 Contact: Akira Shimahara <akira215corp@gmail.com>
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
27 Users: any user space application which wants to communicate with
31 What: /sys/bus/w1/devices/.../ext_power
33 Contact: Akira Shimahara <akira215corp@gmail.com>
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
39 Users: any user space application which wants to communicate with
43 What: /sys/bus/w1/devices/.../resolution
45 Contact: Akira Shimahara <akira215corp@gmail.com>
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.
59 Users: any user space application which wants to communicate with
63 What: /sys/bus/w1/devices/.../temperature
65 Contact: Akira Shimahara <akira215corp@gmail.com>
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.
78 Users: any user space application which wants to communicate with
82 What: /sys/bus/w1/devices/.../w1_slave
84 Contact: Akira Shimahara <akira215corp@gmail.com>
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
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
94 * Anything else: do nothing
95 refer to Documentation/w1/slaves/w1_therm.rst for detailed
97 Users: any user space application which wants to communicate with
101 What: /sys/bus/w1/devices/w1_bus_masterXX/therm_bulk_read
103 Contact: Akira Shimahara <akira215corp@gmail.com>
105 (RW) trigger a bulk read conversion. read the status
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
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).
118 Users: any user space application which wants to communicate with
122 What: /sys/bus/w1/devices/.../conv_time
124 Contact: Ivan Zaentsev <ivan.zaentsev@wirenboard.ru>
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
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
138 other positive value:
139 Set the conversion time in milliseconds.
141 Users: An application using the w1_term device
144 What: /sys/bus/w1/devices/.../features
146 Contact: Ivan Zaentsev <ivan.zaentsev@wirenboard.ru>
148 (RW) Control optional driver settings.
149 Bit masks to read/write (bitwise OR):
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.
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.
160 *read*: Currently selected features.
161 *write*: Select features.
163 Users: An application using the w1_term device