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.Dd June 1, 2014 26.Dt TI_ADC 4 27.Os 28.Sh NAME 29.Nm ti_adc 30.Nd TI AM3XXX analog to digital converter driver 31.Sh SYNOPSIS 32.Cd "device ti_adc" 33.Sh DESCRIPTION 34The 35.Nm 36driver provides access to the AIN (analog inputs) on am3xxx SoCs. 37.Pp 38It provides raw readings of the converted values for each analog inputs. 39.Pp 40The access to 41.Nm 42data is made via the 43.Xr sysctl 8 44interface: 45.Bd -literal 46dev.ti_adc.0.%desc: TI ADC controller 47dev.ti_adc.0.%driver: ti_adc 48dev.ti_adc.0.%pnpinfo: name=adc@44E0D000 compat=ti,adc 49dev.ti_adc.0.%parent: simplebus0 50dev.ti_adc.0.clockdiv: 2400 51dev.ti_adc.0.ain.0.enable: 0 52dev.ti_adc.0.ain.0.open_delay: 0 53dev.ti_adc.0.ain.0.samples_avg: 0 54dev.ti_adc.0.ain.0.input: 0 55dev.ti_adc.0.ain.1.enable: 0 56dev.ti_adc.0.ain.1.open_delay: 0 57dev.ti_adc.0.ain.1.samples_avg: 0 58dev.ti_adc.0.ain.1.input: 0 59dev.ti_adc.0.ain.2.enable: 0 60dev.ti_adc.0.ain.2.open_delay: 0 61dev.ti_adc.0.ain.2.samples_avg: 0 62dev.ti_adc.0.ain.2.input: 0 63dev.ti_adc.0.ain.3.enable: 0 64dev.ti_adc.0.ain.3.open_delay: 0 65dev.ti_adc.0.ain.3.samples_avg: 0 66dev.ti_adc.0.ain.3.input: 0 67dev.ti_adc.0.ain.4.enable: 0 68dev.ti_adc.0.ain.4.open_delay: 0 69dev.ti_adc.0.ain.4.samples_avg: 0 70dev.ti_adc.0.ain.4.input: 0 71dev.ti_adc.0.ain.5.enable: 0 72dev.ti_adc.0.ain.5.open_delay: 0 73dev.ti_adc.0.ain.5.samples_avg: 0 74dev.ti_adc.0.ain.5.input: 0 75dev.ti_adc.0.ain.6.enable: 1 76dev.ti_adc.0.ain.6.open_delay: 0 77dev.ti_adc.0.ain.6.samples_avg: 4 78dev.ti_adc.0.ain.6.input: 2308 79dev.ti_adc.0.ain.7.enable: 1 80dev.ti_adc.0.ain.7.open_delay: 0 81dev.ti_adc.0.ain.7.samples_avg: 0 82dev.ti_adc.0.ain.7.input: 3812 83.Ed 84.Pp 85On Beaglebone-black the analog input 7 is connected to the 3V3B rail through 86a voltage divisor (2:1). 87The 3V3B voltage rail comes from the TL5209 LDO regulator which is limited 88to 500mA maximum. 89.Pp 90Global settings: 91.Bl -tag -width ".Va dev.ti_adc.0.clockdiv" 92.It Va dev.ti_adc.0.clockdiv 93Sets the ADC clock prescaler. 94The minimum value is 10 and the maximum is 65535. 95The ADC clock is based on CLK_M_OSC (24Mhz) / clockdiv. 96This gives a maximum of ~2.4Mhz for the ADC clock and ~10Khz for the default 97setting (clockdiv = 2400). 98.El 99.Pp 100Settings per input: 101.Bl -tag -width ".Va dev.ti_adc.0.ain.%d.samples_avg" 102.It Va dev.ti_adc.0.ain.%d.enable 103Enable the conversion for the input. 104Each input should be individually enabled before it can be used. 105When all the inputs are disabled, the ADC is turned off. 106.It Va dev.ti_adc.0.ain.%d.open_delay 107Sets the number of ADC clock cycles to wait after applying the input 108configuration and before start the ADC conversion. 109.It Va dev.ti_adc.0.ain.%d.samples_avg 110Sets the number of samples average used on each input, it can be set to 0 111(no samples average), 2, 4, 8, or 16. 112.It Va dev.ti_adc.0.ain.%d.input 113Is the converted raw value of the voltage applied on the analog input. 114It is made of a 12 bit value (0 ~ 4095). 115.El 116.Sh SEE ALSO 117.Xr sysctl 8 118.Sh HISTORY 119The 120.Nm 121driver first appeared in 122.Fx 10.1 . 123.Sh AUTHORS 124.An -nosplit 125The driver and this manual page was written by 126.An Luiz Otavio O Souza Aq Mt loos@FreeBSD.org . 127