2 .\" Copyright (c) 2014 Luiz Otavio O Souza <loos@freebsd.org>
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32 .Nd lm75 i2c digital temperature sensor driver
40 driver provides access to sensor data and configuration over the
43 It provides an easy and simple way to check the functionality of an i2c bus
44 as it provides read and write access to the
46 configuration register.
54 dev.lm75.0.%desc: LM75 temperature sensor
55 dev.lm75.0.%driver: lm75
56 dev.lm75.0.%location: addr=0x49
57 dev.lm75.0.%pnpinfo: name=lm750 compat=national,lm75
58 dev.lm75.0.%parent: iicbus3
59 dev.lm75.0.temperature: 27.1C
60 dev.lm75.0.thyst: 75.0C
63 dev.lm75.0.mode: comparator
64 dev.lm75.0.polarity: active-low
65 dev.lm75.0.shutdown: 0
67 .Bl -tag -width ".Va dev.lm75.%d.temperature"
68 .It Va dev.lm75.%d.temperature
69 Is the read-only value of the current temperature read by the sensor.
70 .It Va dev.lm75.%d.thyst
71 Sets the hysteresis temperature.
72 Once the temperature gets over the overtemperature shutdown value (tos)
73 it needs to drop below the hysteresis temperature to disable the output
74 (interrupt) pin again.
75 .It Va dev.lm75.%d.tos
76 Sets the overtemperature shutdown value.
77 Once the temperature gets over this value the output pin will be enabled.
78 The way the output (interrupt) pin works, depends on the mode configuration.
79 .It Va dev.lm75.%d.faults
80 Is the number of faults that must occur consecutively to activate the
81 interrupt (output) pin.
82 It can be set to 1, 2, 4, and 6.
83 .It Va dev.lm75.%d.mode
84 Sets the operation mode for the sensor interrupt pin.
85 It can be set to 'comparator' (default) or 'interrupt'.
86 .It Va dev.lm75.%d.polarity
87 Sets the polarity of the sensor interrupt pin.
88 It can be set to 'active-low' (default) or 'active-high'.
89 Please note that the output pin is an open-drain output and it needs a
90 proper pull-up resistor to work.
91 .It Va dev.lm75.%d.shutdown
92 When set to '1' it shuts down the sensor.
93 The temperature conversion stops but the sensor remains with its i2c bus
94 active, i.e., it can be woken up by setting this option to '0' again.
99 datasheet for more details.
101 When used together with
103 it allows the monitoring of
105 temperature data over SNMP.
109 driver supports both the low and the high resolution models.
111 The low resolution model (lm75) provides a 9 bit output with the LSB
114 The high resolution model (lm75a) provides an 11 bit output with the LSB
117 The driver tries to auto-detect the
119 model, but the detection of some
121 clones may not work reliably.
125 based system, such as
127 these values are configurable for
129 .Bl -tag -width ".Va hint.lm75.%d.addr"
130 .It Va hint.lm75.%d.at
133 you are attaching to.
134 .It Va hint.lm75.%d.addr
143 based system, such as
147 device usually looks like:
150 /* Properties describing the controller appear here. */
153 compatible = "national,lm75";
160 .Bl -tag -width ".Va compatible"
162 Should always be set to "national,lm75".
164 Indicates which 7-bit i2c address the
168 temperature sensors can be wired to 8 different addresses, allowing up to 8
181 driver first appeared in
187 driver and this manual page were written by
188 .An Luiz Otavio O Souza Aq Mt loos@FreeBSD.org .