855feb6867
The ADC has a 12bit resolution and its raw output can be read via sysctl(8) interface. The driver allows the setup of ADC clock, samples average and open delay (the number of clock cycles to wait before start the conversion). The TSC_ADC module is set in the general purpose mode (no touchscreen support). Tested on Beaglebone-black. Written based on AM335x TRM. Reviewed by: rpaulo Approved by: adrian (mentor) Tested by: me, Brian J. McGovern, Sulev-Madis Silber (ketas)
120 lines
4.0 KiB
Groff
120 lines
4.0 KiB
Groff
.\"
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.\" Copyright (c) 2014 Luiz Otavio O Souza <loos@freebsd.org>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd March 21, 2014
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.Dt TI_ADC 4
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.Os
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.Sh NAME
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.Nm ti_adc
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.Nd TI AM3XXX analog to digital converter driver
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.Sh SYNOPSIS
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.Cd "device ti_adc"
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.Sh DESCRIPTION
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The
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.Nm
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driver provides access to the AIN (analog inputs) on am3xxx SoCs.
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.Pp
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It provides raw readings of the converted values for each analog inputs.
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.Pp
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The access to
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.Nm
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data is made via the
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.Xr sysctl 8
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interface:
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.Bd -literal
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dev.ti_adc.0.%desc: TI ADC controller
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dev.ti_adc.0.%driver: ti_adc
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dev.ti_adc.0.%pnpinfo: name=adc@44E0D000 compat=ti,adc
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dev.ti_adc.0.%parent: simplebus0
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dev.ti_adc.0.clockdiv: 2400
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dev.ti_adc.0.ain.0.enable: 0
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dev.ti_adc.0.ain.0.open_delay: 0
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dev.ti_adc.0.ain.0.samples_avg: 0
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dev.ti_adc.0.ain.0.input: 0
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dev.ti_adc.0.ain.1.enable: 0
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dev.ti_adc.0.ain.1.open_delay: 0
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dev.ti_adc.0.ain.1.samples_avg: 0
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dev.ti_adc.0.ain.1.input: 0
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dev.ti_adc.0.ain.2.enable: 0
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dev.ti_adc.0.ain.2.open_delay: 0
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dev.ti_adc.0.ain.2.samples_avg: 0
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dev.ti_adc.0.ain.2.input: 0
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dev.ti_adc.0.ain.3.enable: 0
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dev.ti_adc.0.ain.3.open_delay: 0
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dev.ti_adc.0.ain.3.samples_avg: 0
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dev.ti_adc.0.ain.3.input: 0
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dev.ti_adc.0.ain.4.enable: 0
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dev.ti_adc.0.ain.4.open_delay: 0
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dev.ti_adc.0.ain.4.samples_avg: 0
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dev.ti_adc.0.ain.4.input: 0
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dev.ti_adc.0.ain.5.enable: 0
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dev.ti_adc.0.ain.5.open_delay: 0
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dev.ti_adc.0.ain.5.samples_avg: 0
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dev.ti_adc.0.ain.5.input: 0
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dev.ti_adc.0.ain.6.enable: 1
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dev.ti_adc.0.ain.6.open_delay: 0
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dev.ti_adc.0.ain.6.samples_avg: 4
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dev.ti_adc.0.ain.6.input: 2308
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.Ed
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.Pp
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Global settings:
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.Bl -tag -width ".Va dev.ti_adc.0.clockdiv"
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.It Va dev.ti_adc.0.clockdiv
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Sets the ADC clock prescaler.
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The minimum value is 10 and the maximum is 65535.
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The ADC clock is based on CLK_M_OSC (24Mhz) / clockdiv.
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This gives a maximum of ~2.4Mhz for the ADC clock and ~10Khz for the default
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setting (clockdiv = 2400).
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.El
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.Pp
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Settings per input:
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.Bl -tag -width ".Va dev.ti_adc.0.ain.%d.samples_avg"
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.It Va dev.ti_adc.0.ain.%d.enable
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Enable the conversion for the input.
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Each input should be individually enabled before it can be used.
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When all the inputs are disabled, the ADC is turned off.
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.It Va dev.ti_adc.0.ain.%d.open_delay
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Sets the number of ADC clock cycles to wait after applying the input
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configuration and before start the ADC conversion.
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.It Va dev.ti_adc.0.ain.%d.samples_avg
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Sets the number of samples average used on each input, it can be set to 0
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(no samples average), 2, 4, 8, or 16.
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.It Va dev.ti_adc.0.ain.%d.input
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Is the converted raw value of the voltage applied on the analog input.
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It is made of a 12 bit value (0 ~ 4095).
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.El
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.Sh SEE ALSO
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.Xr sysctl 8
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.Sh HISTORY
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The
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.Nm
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driver first appeared in
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.Fx 11.0 .
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.Sh AUTHORS
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.An -nosplit
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The driver and this manual page was written by
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.An Luiz Otavio O Souza Aq loos@FreeBSD.org
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