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LM75(4)			 BSD Kernel Interfaces Manual		       LM75(4)

     lm75 -- lm75 i2c digital temperature sensor driver

     device iic
     device iicbus
     device lm75

     The lm75 driver provides access to	sensor data and	configuration over the

     It	provides an easy and simple way	to check the functionality of an i2c
     bus as it provides	read and write access to the lm75 configuration	regis-

     The access	to lm75	data is	made via the sysctl(8) interface:

     dev.lm75.0.%desc: LM75 temperature	sensor
     dev.lm75.0.%driver: lm75
     dev.lm75.0.%location: addr=0x49
     dev.lm75.0.%pnpinfo: name=lm750 compat=national,lm75
     dev.lm75.0.%parent: iicbus3
     dev.lm75.0.temperature: 27.1C
     dev.lm75.0.thyst: 75.0C
     dev.lm75.0.tos: 80.0C
     dev.lm75.0.faults:	1
     dev.lm75.0.mode: comparator
     dev.lm75.0.polarity: active-low
     dev.lm75.0.shutdown: 0

     dev.lm75.%d.temperature  Is the read-only value of	the current tempera-
			      ture read	by the sensor.

     dev.lm75.%d.thyst	      Sets the hysteresis temperature.	Once the tem-
			      perature gets over the overtemperature shutdown
			      value (tos) it needs to drop below the hystere-
			      sis temperature to disable the output (inter-
			      rupt) pin	again.

     dev.lm75.%d.tos	      Sets the overtemperature shutdown	value.	Once
			      the temperature gets over	this value the output
			      pin will be enabled.  The	way the	output (inter-
			      rupt) pin	works, depends on the mode configura-

     dev.lm75.%d.faults	      Is the number of faults that must	occur consecu-
			      tively to	activate the interrupt (output)	pin.
			      It can be	set to 1, 2, 4,	and 6.

     dev.lm75.%d.mode	      Sets the operation mode for the sensor interrupt
			      pin.  It can be set to 'comparator' (default) or

     dev.lm75.%d.polarity     Sets the polarity	of the sensor interrupt	pin.
			      It can be	set to 'active-low' (default) or 'ac-
			      tive-high'.  Please note that the	output pin is
			      an open-drain output and it needs	a proper pull-
			      up resistor to work.

     dev.lm75.%d.shutdown     When set to '1' it shuts down the	sensor.	 The
			      temperature conversion stops but the sensor re-
			      mains with its i2c bus active, i.e., it can be
			      woken up by setting this option to '0' again.

     Please check the lm75 datasheet for more details.

     When used together	with snmp_lm75(3) it allows the	monitoring of lm75
     temperature data over SNMP.

     The lm75 driver supports both the low and the high	resolution models.

     The low resolution	model (lm75) provides a	9 bit output with the LSB rep-
     resenting 0.5C.

     The high resolution model (lm75a) provides	an 11 bit output with the LSB
     representing 0.125C.

     The driver	tries to auto-detect the lm75 model, but the detection of some
     lm75 clones may not work reliably.

     On	a device.hints(5) based	system,	such as	MIPS, these values are config-
     urable for	lm75:	Is the iicbus(4) you are attaching to.

     hint.lm75.%d.addr	Is the lm75 i2c	address	on the iicbus(4).

     On	a FDT(4) based system, such as ARM, the	DTS part for a lm75 device
     usually looks like:

     i2c {
	     /*	Properties describing the controller appear here. */
	     lm750@49 {
		     compatible	= "national,lm75";
		     reg = <0x49>;


     compatible	 Should	always be set to "national,lm75".

     reg	 Indicates which 7-bit i2c address the lm75 is wired at.  lm75
		 temperature sensors can be wired to 8 different addresses,
		 allowing up to	8 sensors on the same iicbus(4).

     snmp_lm75(3), fdt(4), iic(4), iicbus(4), sysctl(8)

     The lm75 driver first appeared in FreeBSD 11.0.

     The lm75 driver and this manual page were written by Luiz Otavio O	Souza

BSD			       December	26, 2017			   BSD


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