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ADS111x(4)	       FreeBSD Kernel Interfaces Manual		    ADS111x(4)

     ads111x --	driver for ADS101x and ADS111x i2c analog to digital convert-

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

	   device ads111x

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


     The ads111x driver	provides support for the ADS101x/ADS111x family	of
     analog to digital converter (ADC) devices.	 The supported devices are all
     similar to	each other, varying in features	such as	resolution and number
     of	input channels.	 The devices offer a number of configuration options
     which can be set via hints, FDT data, and sysctl(8).

     Sysctl(8) provides	access to the voltage measurements made	by the device.
     Each time the dev.ads111x._unit_._channel_.voltage	variable is accessed
     for a given channel, the driver switches the chip's internal mux to
     choose the	right input pins for that channel, directs it to make a	single
     measurement, and returns the measured value in microvolts.	 The amount of
     time required to make the measurement is a	function of the	sampling rate
     configured	for the	device.	 While device is directed to make a single
     measurement, it still averages the	input values for the same amount of
     time as it	would to emit one sample if it were in continuous mode.	 For
     example, if the sample rate were configured as 125	samples	per second, a
     single measurement	would require 8	milliseconds.

     For devices that support multiple input pins, the device datasheet	de-
     scribes mux settings to control how those pins are	interpeted when	making
     either single-ended or differential measurements.	There are eight	possi-
     ble ways to combine the inputs from the four pins.	 The ads111x driver
     models that by creating a separate	output channel for each	of the eight
     combinations.  To make a measurement on a given pin or pair of pins, you
     simply access the voltage variable	for the	channel	number that corre-
     sponds the	mux setting number (0 through 7) shown in the datasheet.  When
     the driver	is configured with hints or FDT	data, it creates sysctl	vari-
     ables for just the	channels specified in the config data.	When there is
     no	channel	config data, it	creates	all eight possible channels so that
     you can access whichever one(s) you need.

     For devices that include an alert output pin, the ads111x driver does not
     directly support the pin in terms of sensing or acting on changes in the
     pin state.	 However, you may connect the pin to a gpio input or fan con-
     troller or	other external device, and use the driver's sysctl variables
     to	configure behavior and threshold values	for the	pin.  The driver
     avoids perturbing your settings as	it does	other manipulations to the
     config register.

     Sysctl variables are used to access the voltage measurements, and to
     change the	configuration of the channels.	All writeable variables	may
     also be set as loader(8) tunables.	 Channel numbers in these sysctl vari-
     ables range from 0	through	7.

	     Provides access to	the configuration register bits	that control
	     the alert pin configuration.  Other bits which are	controlled by
	     the driver	are masked out,	and cannot be viewed or	changed	using
	     this variable.

	     Sets the low threshold for	activating the alert pin.

	     Sets the high threshold for activating the	alert pin.

	     Sets the sample rate for the channel.  The	device datasheet docu-
	     ments eight available sample rates, chosen	by setting a value of
	     0 through 7 into the corresponding	control	register bits.	This
	     variable sets the value used for those bits when making a mea-
	     surement on the given channel.

	     Because measurements are always made in single-shot mode, think
	     of	this variable as controlling the averaging time	for a single
	     sample; the time to make a	measurement is 1 / samplerate.

	     Sets the programmable gain	amplifier for the channel on devices
	     which have	an internal amplifier.	The device datasheet documents
	     eight available gain values, chosen by setting a value of 0
	     through 7 into the	corresponding control register bits.  This
	     variable sets the value used for those bits when making a mea-
	     surement on the given channel.

	     Reading this variable causes the device to	make a measurement on
	     the corresponding input pin(s) and	return the voltage in micro-

	     Note that this variable does not appear when you list multiple
	     sysctl variables -- you must access it specifically by name, be-
	     cause accessing it	triggers device	I/O.

     The ads111x driver	provides support for the following devices:

	   ADS1013     ADS1113
	   ADS1014     ADS1114
	   ADS1015     ADS1115

     On	an fdt(4) based	system,	the ads111x device is defined as a slave de-
     vice subnode of the i2c bus controller node.  All properties documented
     in	the ads1015.txt	bindings document can be used with the ads111x device.

     The following properties are required in the ads111x device subnode:

	     One of the	following:
		   "ti,ads1013	   "ti,ads1113""
		   "ti,ads1014	   "ti,ads1114""
		   "ti,ads1015	   "ti,ads1115""

     reg     I2c slave address of device.

     Specific channels can be configured by adding child nodes to the ads111x
     node, as described	in the standard	ads1015.txt bindings document.	If no
     channels are configured, sysctl variables will be created for all possi-
     ble channels supported by the device type,	otherwise only the specified
     channels are created.

   Example including channel configuration
	   adc@48 {
	       compatible = "ti,ads1115";
	       reg = <0x48>;
	       status =	"okay";
	       #address-cells =	<1>;
	       #size-cells = <0>;

	       channel@6 {
		   reg = <6>;
		   ti,gain = <3>;
		   ti,datarate = <4>;
	       channel@7 {
		   reg = <7>;
		   ti,gain = <1>;
		   ti,datarate = <7>;

     On	a device.hints(5) based	system,	such as	MIPS, these values are config-
     urable for	ads111x:
	     The iicbus	instance the ads111x instance is attached to.

	     The amplifier gain, as described above for	the sysctl variable

	     The sample	rate, as described above for the sysctl	variable

     If	no channels are	configured, sysctl variables will be created for all
     possible channels supported by the	device type, otherwise only the	speci-
     fied channels are created.

     fdt(4), sysctl(4)

     The ads111x driver	first appeared in FreeBSD 13.0.

FreeBSD	13.0		       September 2, 2019		  FreeBSD 13.0


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