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32 .Nd Dallas Semiconductor 1-Wire Temperature sensor
38 module supports many of the 1-Wire temperature sensors.
40 The sensor is read periodically and the results returned via a
44 These temperature sensors are supported by the
47 .Bl -tag -width MAX31820 -compact
49 1-Wire Digital Thermometer
51 High-Precision 1-Wire Digital Thermometer
53 Programmable Resolution 1-Wire Digital Thermometer
55 Econo 1-Wire Digital Thermometer
57 Programmable Resolution 1-Wire Digital Thermometer with 4-bit ID
59 1-Wire, Parasite-Power, Ambient Temperature Sensor
62 The driver supports Family codes 0x10, 0x22, 0x28, and 0x3b.
66 driver reports data via
68 entries in the device's node in the
71 .Bl -tag -width xxxxxxxxxx
73 The last temperature read, in milli-Kelvin.
75 The number of CRC errors in reading the temperature form the
77 Some CRC errors are to be expected.
78 High rates of CRC errors, however, generally indicate a noisy
79 environment, cabling issues, or too many devices on the bus.
81 The number of times a non-CRC error was encountered reading the temperature
83 This type of error is very rare.
85 The time, in ticks, between successive reads of the sensor.
87 This item is non-zero when the device is connected using its parasitic
89 It can also indicate a wiring error.
92 Temperatures are reported in milli-Kelvin, even though the absolute
93 accuracy is around 0.2 degrees for the good devices and around 1
94 degree for cheaper devices.
95 The devices report in steps of 0.0625 degrees.
96 The driver preserves the precision of the device's measurements
100 These devices often have a much higher relative accuracy and
101 repeatability than their absolute accuracy.
102 This makes them well suited for control loops that strive for
103 stability and become possible if the full precision is preserved.
112 is a registered trademark of Maxim Integrated Products, Inc.
116 driver first appeared in
121 device driver and this manual page were written by
124 The parasitic mode of the devices does not work.
125 It requires support from the
127 driver that is unimplemented.
131 are not recognized or reported.
133 The type of the device is not reported via
136 Alarm mode is not supported.
137 It is not possible to set the low and high alarm temperatures.
139 There is no way to write to the EEPROM.
141 .Dq Convert Temperature
142 requests are sent directly to the device.
143 There is no way to use the broadcast ability of the 1-Wire bus to do
144 all the conversions in parallel.
146 It is not possible to set the precision on those devices that support
149 The time to convert is fixed at 1 second, even though some devices are
152 There is no character device to supply a stream of readings to a
154 Programs interested in the temperature must poll the sysctl to get the