1.\" 2.\" Copyright (c) 2014 Luiz Otavio O Souza <loos@freebsd.org> 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 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 June 1, 2014 28.Dt TI_ADC 4 29.Os 30.Sh NAME 31.Nm ti_adc 32.Nd TI AM3XXX analog to digital converter driver 33.Sh SYNOPSIS 34.Cd "device ti_adc" 35.Sh DESCRIPTION 36The 37.Nm 38driver provides access to the AIN (analog inputs) on am3xxx SoCs. 39.Pp 40It provides raw readings of the converted values for each analog inputs. 41.Pp 42The access to 43.Nm 44data is made via the 45.Xr sysctl 8 46interface: 47.Bd -literal 48dev.ti_adc.0.%desc: TI ADC controller 49dev.ti_adc.0.%driver: ti_adc 50dev.ti_adc.0.%pnpinfo: name=adc@44E0D000 compat=ti,adc 51dev.ti_adc.0.%parent: simplebus0 52dev.ti_adc.0.clockdiv: 2400 53dev.ti_adc.0.ain.0.enable: 0 54dev.ti_adc.0.ain.0.open_delay: 0 55dev.ti_adc.0.ain.0.samples_avg: 0 56dev.ti_adc.0.ain.0.input: 0 57dev.ti_adc.0.ain.1.enable: 0 58dev.ti_adc.0.ain.1.open_delay: 0 59dev.ti_adc.0.ain.1.samples_avg: 0 60dev.ti_adc.0.ain.1.input: 0 61dev.ti_adc.0.ain.2.enable: 0 62dev.ti_adc.0.ain.2.open_delay: 0 63dev.ti_adc.0.ain.2.samples_avg: 0 64dev.ti_adc.0.ain.2.input: 0 65dev.ti_adc.0.ain.3.enable: 0 66dev.ti_adc.0.ain.3.open_delay: 0 67dev.ti_adc.0.ain.3.samples_avg: 0 68dev.ti_adc.0.ain.3.input: 0 69dev.ti_adc.0.ain.4.enable: 0 70dev.ti_adc.0.ain.4.open_delay: 0 71dev.ti_adc.0.ain.4.samples_avg: 0 72dev.ti_adc.0.ain.4.input: 0 73dev.ti_adc.0.ain.5.enable: 0 74dev.ti_adc.0.ain.5.open_delay: 0 75dev.ti_adc.0.ain.5.samples_avg: 0 76dev.ti_adc.0.ain.5.input: 0 77dev.ti_adc.0.ain.6.enable: 1 78dev.ti_adc.0.ain.6.open_delay: 0 79dev.ti_adc.0.ain.6.samples_avg: 4 80dev.ti_adc.0.ain.6.input: 2308 81dev.ti_adc.0.ain.7.enable: 1 82dev.ti_adc.0.ain.7.open_delay: 0 83dev.ti_adc.0.ain.7.samples_avg: 0 84dev.ti_adc.0.ain.7.input: 3812 85.Ed 86.Pp 87On Beaglebone-black the analog input 7 is connected to the 3V3B rail through 88a voltage divisor (2:1). 89The 3V3B voltage rail comes from the TL5209 LDO regulator which is limited 90to 500mA maximum. 91.Pp 92Global settings: 93.Bl -tag -width ".Va dev.ti_adc.0.clockdiv" 94.It Va dev.ti_adc.0.clockdiv 95Sets the ADC clock prescaler. 96The minimum value is 10 and the maximum is 65535. 97The ADC clock is based on CLK_M_OSC (24Mhz) / clockdiv. 98This gives a maximum of ~2.4Mhz for the ADC clock and ~10Khz for the default 99setting (clockdiv = 2400). 100.El 101.Pp 102Settings per input: 103.Bl -tag -width ".Va dev.ti_adc.0.ain.%d.samples_avg" 104.It Va dev.ti_adc.0.ain.%d.enable 105Enable the conversion for the input. 106Each input should be individually enabled before it can be used. 107When all the inputs are disabled, the ADC is turned off. 108.It Va dev.ti_adc.0.ain.%d.open_delay 109Sets the number of ADC clock cycles to wait after applying the input 110configuration and before start the ADC conversion. 111.It Va dev.ti_adc.0.ain.%d.samples_avg 112Sets the number of samples average used on each input, it can be set to 0 113(no samples average), 2, 4, 8, or 16. 114.It Va dev.ti_adc.0.ain.%d.input 115Is the converted raw value of the voltage applied on the analog input. 116It is made of a 12 bit value (0 ~ 4095). 117.El 118.Sh SEE ALSO 119.Xr sysctl 8 120.Sh HISTORY 121The 122.Nm 123driver first appeared in 124.Fx 10.1 . 125.Sh AUTHORS 126.An -nosplit 127The driver and this manual page was written by 128.An Luiz Otavio O Souza Aq Mt loos@FreeBSD.org . 129