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GPIOTHS(4)		    Kernel Interfaces Manual		    GPIOTHS(4)

NAME
       gpioths -- driver for DHTxx and AM320x temperature and humidity sensors

SYNOPSIS
       To  compile  this  driver  into the kernel, place the following line in
       your kernel configuration file:

	     device gpioths

       Alternatively, to load the driver as a module at	boot time,  place  the
       following line in loader.conf(5):

	     gpioths_load="YES"

DESCRIPTION
       The  gpioths driver supports the	DHTxx and AM320x family	of temperature
       and humidity sensors.  The driver automatically reads the  values  from
       the  sensor  once  every	5 seconds, and makes the results available via
       sysctl(8) variables.

HARDWARE
       The gpioths driver provides support for the following devices:

	     DHT11	 DHT12
	     DHT21	 DHT22
	     AM3201	 AM3202

       The supported devices are all similar to	each other, varying  primarily
       in accuracy and resolution.  The	devices	require	a single wire for data
       communications,	using  a  custom protocol which	is not compatible with
       Maxim's 1-wire(tm).  The	AM320x devices also support connection	to  an
       i2c  bus,  but this driver supports only	the single-wire	connection op-
       tion.

SYSCTL VARIABLES
       Sysctl variables	are used to access the most recent temperature and hu-
       midity measurements.

       dev.gpioths.<unit>.temperature
	       The current temperature	in  integer  deciKelvins.   Note  that
	       sysctl(8)  will	convert	 those units to	display	in decimal de-
	       grees Celsius.

       dev.gpioths.<unit>.humidity
	       The current relative humidity, as an integer percentage.

       dev.gpioths.<unit>.fails
	       The number of failed attempts to	communicate  with  the	sensor
	       since the last good access.  Cleared whenever a set of measure-
	       ments is	successfully retrieved.

FDT CONFIGURATION
       On  an  fdt(4) based system, a gpioths device node is typically defined
       directly	under the root node, or	under a	simplebus node that represents
       a collection of devices on a board.

       The following properties	are required in	the gpioths device subnode:

       compatible
	       Must be "dht11".

       gpios   A reference to the gpio device and pin for data communications.

   Example of adding a sensor with an overlay
	     /dts-v1/;
	     /plugin/;
	     #include <dt-bindings/gpio/gpio.h>

	     / {
		 compatible = "wand,imx6q-wandboard";
	     };

	     &{/} {
		 dht0 {
		     compatible	= "dht11";
		     gpios = <&gpio5 15	GPIO_ACTIVE_HIGH>;
		 };
	     };

HINTS CONFIGURATION
       On a device.hints(5) based system, such as MIPS,	these values are  con-
       figurable for gpioths:

       hint.gpioths.<unit>.at
	       The gpiobus(4) instance the gpioths instance is attached	to.

       hint.gpioths.pins
	       A  bitmask  with	a single bit set to indicate which gpio	pin on
	       the gpiobus(4) to use for data communications.

SEE ALSO
       fdt(4), gpiobus(4), sysctl(8)

HISTORY
       The gpioths driver first	appeared in FreeBSD 11.1.

FreeBSD	15.0		       December	8, 2019			    GPIOTHS(4)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=gpioths&sektion=4&manpath=FreeBSD+15.0-RELEASE+and+Ports.quarterly>

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