1.\" 2.\" Copyright (c) 2019 Ian Lepore <ian@freebsd.org> 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 15.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 16.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 17.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 18.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 19.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 20.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 21.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 23.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24.\" 25.\" $FreeBSD$ 26.\" 27.Dd September 2, 2019 28.Dt ADS111x 4 29.Os 30.Sh NAME 31.Nm ads111x 32.Nd driver for ADS101x and ADS111x i2c analog to digital converters 33.Sh SYNOPSIS 34To compile this driver into the kernel, 35place the following line in your 36kernel configuration file: 37.Bd -ragged -offset indent 38.Cd "device ads111x" 39.Ed 40.Pp 41Alternatively, to load the driver as a 42module at boot time, place the following line in 43.Xr loader.conf 5 : 44.Bd -literal -offset indent 45ads111x_load="YES" 46.Ed 47.Sh DESCRIPTION 48The 49.Nm 50driver provides support for the ADS101x/ADS111x family of analog 51to digital converter (ADC) devices. 52The supported devices are all similar to each other, varying in 53features such as resolution and number of input channels. 54The devices offer a number of configuration options which can be 55set via hints, FDT data, and 56.Xr sysctl 8 . 57.Pp 58.Xr Sysctl 8 59provides access to the voltage measurements made by the device. 60Each time the 61.Va dev.ads111x.<unit>.<channel>.voltage 62variable is accessed for a given channel, the driver switches the 63chip's internal mux to choose the right input pins for that channel, 64directs it to make a single measurement, and returns the measured value 65in microvolts. 66The amount of time required to make the measurement is a function 67of the sampling rate configured for the device. 68While device is directed to make a single measurement, it still averages 69the input values for the same amount of time as it would to emit one 70sample if it were in continuous mode. 71For example, if the sample rate were configured as 125 samples per 72second, a single measurement would require 8 milliseconds. 73.Pp 74For devices that support multiple input pins, the device datasheet 75describes mux settings to control how those pins are interpeted when 76making either single-ended or differential measurements. 77There are eight possible ways to combine the inputs from the four pins. 78The 79.Nm 80driver models that by creating a separate output channel for each of 81the eight combinations. 82To make a measurement on a given pin or pair of pins, you simply access 83the voltage variable for the channel number that corresponds the mux 84setting number (0 through 7) shown in the datasheet. 85When the driver is configured with hints or FDT data, it creates 86sysctl variables for just the channels specified in the config data. 87When there is no channel config data, it creates all eight possible 88channels so that you can access whichever one(s) you need. 89.Pp 90For devices that include an 91.Va alert 92output pin, the 93.Nm 94driver does not directly support the pin in terms of sensing or 95acting on changes in the pin state. 96However, you may connect the pin to a gpio input or fan controller 97or other external device, and use the driver's sysctl variables to 98configure behavior and threshold values for the pin. 99The driver avoids perturbing your settings as it does other 100manipulations to the config register. 101.Sh SYSCTL VARIABLES 102Sysctl variables are used to access the voltage measurements, and to 103change the configuration of the channels. 104All writeable variables may also be set as 105.Xr loader 8 106tunables. 107Channel numbers in these sysctl variables range from 0 through 7. 108.Bl -tag -width indent 109.It Va dev.ads111x.<unit>.config 110Provides access to the configuration register bits that control the 111alert pin configuration. 112Other bits which are controlled by the driver are masked out, and 113cannot be viewed or changed using this variable. 114.It Va dev.ads111x.<unit>.lo_thresh 115Sets the low threshold for activating the alert pin. 116.It Va dev.ads111x.<unit>.hi_thresh 117Sets the high threshold for activating the alert pin. 118.It Va dev.ads111x.<unit>.<channel>.rate_index 119Sets the sample rate for the channel. 120The device datasheet documents eight available sample rates, chosen 121by setting a value of 0 through 7 into the corresponding control 122register bits. 123This variable sets the value used for those bits when making a 124measurement on the given channel. 125.Pp 126Because measurements are always made in single-shot mode, think of 127this variable as controlling the averaging time for a single sample; 128the time to make a measurement is 1 / samplerate. 129.It Va dev.ads111x.<unit>.<channel>.gain_index 130Sets the programmable gain amplifier for the channel on devices 131which have an internal amplifier. 132The device datasheet documents eight available gain values, chosen 133by setting a value of 0 through 7 into the corresponding control 134register bits. 135This variable sets the value used for those bits when making a 136measurement on the given channel. 137.It Va dev.ads111x.<unit>.<channel>.voltage 138Reading this variable causes the device to make a measurement on 139the corresponding input pin(s) and return the voltage in microvolts. 140.Pp 141Note that this variable does not appear when you list multiple 142sysctl variables -- you must access it specifically by name, because 143accessing it triggers device I/O. 144.El 145.Sh HARDWARE 146The 147.Nm 148driver provides support for the following devices: 149.Pp 150.Bl -column -compact -offset indent "XXXXXXXX" "XXXXXXXX" 151.It ADS1013 Ta ADS1113 152.It ADS1014 Ta ADS1114 153.It ADS1015 Ta ADS1115 154.El 155.Sh FDT CONFIGURATION 156On an 157.Xr fdt 4 158based system, the 159.Nm 160device is defined as a slave device subnode 161of the i2c bus controller node. 162All properties documented in the 163.Va ads1015.txt 164bindings document can be used with the 165.Nm 166device. 167.Pp 168The following properties are required in the 169.Nm 170device subnode: 171.Bl -tag -width indent 172.It Va compatible 173One of the following: 174.Bl -column -compact -offset indent ".Dq ti,ads1013" ".Dq ti,ads1113" 175.It Dq ti,ads1013 Ta Dq ti,ads1113 176.It Dq ti,ads1014 Ta Dq ti,ads1114 177.It Dq ti,ads1015 Ta Dq ti,ads1115 178.El 179.It Va reg 180I2c slave address of device. 181.El 182.Pp 183Specific channels can be configured by adding child nodes to the 184.Nm 185node, as described in the standard ads1015.txt bindings document. 186If no channels are configured, sysctl variables will be created 187for all possible channels supported by the device type, otherwise 188only the specified channels are created. 189.Ss Example including channel configuration 190.Bd -unfilled -offset indent 191adc@48 { 192 compatible = "ti,ads1115"; 193 reg = <0x48>; 194 status = "okay"; 195 #address-cells = <1>; 196 #size-cells = <0>; 197 198 channel@6 { 199 reg = <6>; 200 ti,gain = <3>; 201 ti,datarate = <4>; 202 }; 203 channel@7 { 204 reg = <7>; 205 ti,gain = <1>; 206 ti,datarate = <7>; 207 }; 208}; 209.Ed 210.Sh HINTS CONFIGURATION 211On a 212.Xr device.hints 5 213based system, such as 214.Li MIPS , 215these values are configurable for 216.Nm : 217.Bl -tag -width indent 218.It Va hint.ads111x.<unit>.at 219The iicbus instance the 220.Nm 221instance is attached to. 222.It Va hint.ads111x.<unit>.<channel>.gain_index 223The amplifier gain, as described above for the sysctl variable 224.Va dev.ads111x.<unit>.<channel>.gain_index . 225.It Va hint.ads111x.<unit>.<channel>.rate_index 226The sample rate, as described above for the sysctl variable 227.Va dev.ads111x.<unit>.<channel>.rate_index . 228.El 229.Pp 230If no channels are configured, sysctl variables will be created 231for all possible channels supported by the device type, otherwise 232only the specified channels are created. 233.Sh SEE ALSO 234.Xr fdt 4 , 235.Xr sysctl 8 236.Sh HISTORY 237The 238.Nm 239driver first appeared in 240.Fx 13.0 . 241