129 lines
4.3 KiB
Groff
129 lines
4.3 KiB
Groff
.\"
|
|
.\" Copyright (c) 2014 Luiz Otavio O Souza <loos@freebsd.org>
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
|
|
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
|
|
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
|
|
.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
|
|
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
|
|
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
|
.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
|
.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
|
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
|
|
.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
.\"
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd June 1, 2014
|
|
.Dt TI_ADC 4
|
|
.Os
|
|
.Sh NAME
|
|
.Nm ti_adc
|
|
.Nd TI AM3XXX analog to digital converter driver
|
|
.Sh SYNOPSIS
|
|
.Cd "device ti_adc"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Nm
|
|
driver provides access to the AIN (analog inputs) on am3xxx SoCs.
|
|
.Pp
|
|
It provides raw readings of the converted values for each analog inputs.
|
|
.Pp
|
|
The access to
|
|
.Nm
|
|
data is made via the
|
|
.Xr sysctl 8
|
|
interface:
|
|
.Bd -literal
|
|
dev.ti_adc.0.%desc: TI ADC controller
|
|
dev.ti_adc.0.%driver: ti_adc
|
|
dev.ti_adc.0.%pnpinfo: name=adc@44E0D000 compat=ti,adc
|
|
dev.ti_adc.0.%parent: simplebus0
|
|
dev.ti_adc.0.clockdiv: 2400
|
|
dev.ti_adc.0.ain.0.enable: 0
|
|
dev.ti_adc.0.ain.0.open_delay: 0
|
|
dev.ti_adc.0.ain.0.samples_avg: 0
|
|
dev.ti_adc.0.ain.0.input: 0
|
|
dev.ti_adc.0.ain.1.enable: 0
|
|
dev.ti_adc.0.ain.1.open_delay: 0
|
|
dev.ti_adc.0.ain.1.samples_avg: 0
|
|
dev.ti_adc.0.ain.1.input: 0
|
|
dev.ti_adc.0.ain.2.enable: 0
|
|
dev.ti_adc.0.ain.2.open_delay: 0
|
|
dev.ti_adc.0.ain.2.samples_avg: 0
|
|
dev.ti_adc.0.ain.2.input: 0
|
|
dev.ti_adc.0.ain.3.enable: 0
|
|
dev.ti_adc.0.ain.3.open_delay: 0
|
|
dev.ti_adc.0.ain.3.samples_avg: 0
|
|
dev.ti_adc.0.ain.3.input: 0
|
|
dev.ti_adc.0.ain.4.enable: 0
|
|
dev.ti_adc.0.ain.4.open_delay: 0
|
|
dev.ti_adc.0.ain.4.samples_avg: 0
|
|
dev.ti_adc.0.ain.4.input: 0
|
|
dev.ti_adc.0.ain.5.enable: 0
|
|
dev.ti_adc.0.ain.5.open_delay: 0
|
|
dev.ti_adc.0.ain.5.samples_avg: 0
|
|
dev.ti_adc.0.ain.5.input: 0
|
|
dev.ti_adc.0.ain.6.enable: 1
|
|
dev.ti_adc.0.ain.6.open_delay: 0
|
|
dev.ti_adc.0.ain.6.samples_avg: 4
|
|
dev.ti_adc.0.ain.6.input: 2308
|
|
dev.ti_adc.0.ain.7.enable: 1
|
|
dev.ti_adc.0.ain.7.open_delay: 0
|
|
dev.ti_adc.0.ain.7.samples_avg: 0
|
|
dev.ti_adc.0.ain.7.input: 3812
|
|
.Ed
|
|
.Pp
|
|
On Beaglebone-black the analog input 7 is connected to the 3V3B rail through
|
|
a voltage divisor (2:1).
|
|
The 3V3B voltage rail comes from the TL5209 LDO regulator which is limited
|
|
to 500mA maximum.
|
|
.Pp
|
|
Global settings:
|
|
.Bl -tag -width ".Va dev.ti_adc.0.clockdiv"
|
|
.It Va dev.ti_adc.0.clockdiv
|
|
Sets the ADC clock prescaler.
|
|
The minimum value is 10 and the maximum is 65535.
|
|
The ADC clock is based on CLK_M_OSC (24Mhz) / clockdiv.
|
|
This gives a maximum of ~2.4Mhz for the ADC clock and ~10Khz for the default
|
|
setting (clockdiv = 2400).
|
|
.El
|
|
.Pp
|
|
Settings per input:
|
|
.Bl -tag -width ".Va dev.ti_adc.0.ain.%d.samples_avg"
|
|
.It Va dev.ti_adc.0.ain.%d.enable
|
|
Enable the conversion for the input.
|
|
Each input should be individually enabled before it can be used.
|
|
When all the inputs are disabled, the ADC is turned off.
|
|
.It Va dev.ti_adc.0.ain.%d.open_delay
|
|
Sets the number of ADC clock cycles to wait after applying the input
|
|
configuration and before start the ADC conversion.
|
|
.It Va dev.ti_adc.0.ain.%d.samples_avg
|
|
Sets the number of samples average used on each input, it can be set to 0
|
|
(no samples average), 2, 4, 8, or 16.
|
|
.It Va dev.ti_adc.0.ain.%d.input
|
|
Is the converted raw value of the voltage applied on the analog input.
|
|
It is made of a 12 bit value (0 ~ 4095).
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr sysctl 8
|
|
.Sh HISTORY
|
|
The
|
|
.Nm
|
|
driver first appeared in
|
|
.Fx 10.1 .
|
|
.Sh AUTHORS
|
|
.An -nosplit
|
|
The driver and this manual page was written by
|
|
.An Luiz Otavio O Souza Aq Mt loos@FreeBSD.org .
|