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31 .Nd Dallas Semiconductor 1-Wire Temperature sensor
37 module supports many of the 1-Wire temperature sensors.
39 The sensor is read periodically and the results returned via a
43 These temperature sensors are supported by the
46 .Bl -tag -width MAX31820 -compact
48 1-Wire Digital Thermometer
50 High-Precision 1-Wire Digital Thermometer
52 Programmable Resolution 1-Wire Digital Thermometer
54 Econo 1-Wire Digital Thermometer
56 Programmable Resolution 1-Wire Digital Thermometer with 4-bit ID
58 1-Wire, Parasite-Power, Ambient Temperature Sensor
61 The driver supports Family codes 0x10, 0x22, 0x28, and 0x3b.
65 driver reports data via
67 entries in the device's node in the
70 .Bl -tag -width xxxxxxxxxx
72 The last temperature read, in milli-Kelvin.
74 The number of CRC errors in reading the temperature form the
76 Some CRC errors are to be expected.
77 High rates of CRC errors, however, generally indicate a noisy
78 environment, cabling issues, or too many devices on the bus.
80 The number of times a non-CRC error was encountered reading the temperature
82 This type of error is very rare.
84 The time, in ticks, between successive reads of the sensor.
86 This item is non-zero when the device is connected using its parasitic
88 It can also indicate a wiring error.
91 Temperatures are reported in milli-Kelvin, even though the absolute
92 accuracy is around 0.2 degrees for the good devices and around 1
93 degree for cheaper devices.
94 The devices report in steps of 0.0625 degrees.
95 The driver preserves the precision of the device's measurements
99 These devices often have a much higher relative accuracy and
100 repeatability than their absolute accuracy.
101 This makes them well suited for control loops that strive for
102 stability and become possible if the full precision is preserved.
111 is a registered trademark of Maxim Integrated Products, Inc.
115 driver first appeared in
120 device driver and this manual page were written by
123 The parasitic mode of the devices does not work.
124 It requires support from the
126 driver that is unimplemented.
130 are not recognized or reported.
132 The type of the device is not reported via
135 Alarm mode is not supported.
136 It is not possible to set the low and high alarm temperatures.
138 There is no way to write to the EEPROM.
140 .Dq Convert Temperature
141 requests are sent directly to the device.
142 There is no way to use the broadcast ability of the 1-Wire bus to do
143 all the conversions in parallel.
145 It is not possible to set the precision on those devices that support
148 The time to convert is fixed at 1 second, even though some devices are
151 There is no character device to supply a stream of readings to a
153 Programs interested in the temperature must poll the sysctl to get the