William, Rather you should not comment on my replies. If I say white, you say black even when you know you are wrong. If you look at the DT overlay the OP referenced, the additional entries don’t exist and that is why I posted an updated DT overlay. Reading in_voltagex_raw like your beaglebone-black-adc example was never meant for high speed capture. In fact you are just reading the same sample over and over again. Reading the buffer via /dev/iio:device0 is how you are supposed to read IIO ADC samples. If you want to understand oversampling, open delay, sample delay, then read the AM3358 TRM.
Regards, John > On Mar 9, 2016, at 12:58 AM, William Hermans <yyrk...@gmail.com> wrote: > > Now if you want to convey more information that is actually *useful* to > anyone reading this post. You can say that both voltageX_raw, and iio:deviceX > are buffers. > > With voltageX_raw being a single value buffer that gets updated only once > every open() call on it's file descriptor. > > Where iio:deviceX is a buffer, defined in size by the value set in > /sys/bus/iio/devices/iio\:device0/buffer/length > > More *useful* information can be found here: > http://processors.wiki.ti.com/index.php/AM335x_ADC_Driver's_Guide > <http://processors.wiki.ti.com/index.php/AM335x_ADC_Driver's_Guide>. Then if > you want even more information still, googling "iio" will produce a lot of > information. Much of it not so useful. At least for our use case, the > Beaglebone. > > On Wed, Mar 9, 2016 at 1:47 AM, William Hermans <yyrk...@gmail.com > <mailto:yyrk...@gmail.com>> wrote: > what the hell does what you've said there even mean John ? voltagex_raw is > one shot mode, iio:deviceX is continuous mode. > > What you said above only serves to confuse the situation. > > On Wed, Mar 9, 2016 at 1:32 AM, John Syne <john3...@gmail.com > <mailto:john3...@gmail.com>> wrote: > /* > * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com/ > <http://www.ti.com/> > * > * This program is free software; you can redistribute it and/or modify > * it under the terms of the GNU General Public License version 2 as > * published by the Free Software Foundation. > */ > /dts-v1/; > /plugin/; > > / { > compatible = "ti,beaglebone", "ti,beaglebone-black", > "ti,beaglebone-green"; > > /* identification */ > part-number = "BB-ADC"; > version = "00A0"; > > /* state the resources this cape uses */ > exclusive-use = > /* the pin header uses */ > "P9.31", /* AIN0 */ > "P9.40", /* AIN1 */ > "P9.37", /* AIN2 */ > "P9.38", /* AIN3 */ > "P9.33", /* AIN4 */ > "P9.36", /* AIN5 */ > "P9.35", /* AIN6 */ > /* the hardware ip uses */ > "tscadc"; > > fragment@0 { > target = <&tscadc>; > __overlay__ { > > status = "okay"; > adc { > ti,adc-channels = <0 1 2 3 4 5 6>; > ti,chan-step-avg = <0x16 0x16 0x16 0x16 0x16 > 0x16 0x16>; > ti,chan-step-opendelay = <0x98 0x98 0x98 0x98 > 0x98 0x98 0x98>; > ti,chan-step-sampledelay = <0x0 0x0 0x0 0x0 0x0 > 0x0 0x0>; > }; > }; > }; > }; > > Reading from /sys/bus/iio/devices/iio:device0/in_voltage0_raw is reading and > attribute of the IIO driver. Reading from /dev/iio:device0 is reading from > the same IIO driver, but in this case you are reading from the buffer which > stores samples defined in the DT overlay above. > > Regards, > John > > > > >> On Mar 8, 2016, at 9:51 PM, Audrey <a...@smith.edu <mailto:a...@smith.edu>> >> wrote: >> >> Thanks for the reply John. Could you perhaps explain how to modify the >> oversample, open delay time, and sample time in greater detail in the BB-ADC >> overlay? I do not see these variables in the dto in github >> (https://github.com/beagleboard/devicetree-source/blob/master/arch/arm/boot/dts/BB-ADC-00A0.dts >> >> <https://github.com/beagleboard/devicetree-source/blob/master/arch/arm/boot/dts/BB-ADC-00A0.dts>). >> Also, what value can/should I change them to? >> >> So just to clarify, reading from >> /sys/bus/iio/devices/iio:device0/in_voltage0_raw reads attributes using >> sysfs, while reading from /dev/iio:device0 reads the values using IIO? Also >> another conceptual question, can you explain what exactly is in_voltage0_raw >> and iio:device0? I know it's not a folder, and I interact with it by using >> cat. So is it just like a text file or something? >> >> Thanks. >> >> On Sunday, March 6, 2016 at 2:15:17 PM UTC-5, john3909 wrote: >> That is because you are doing this wrong. Reading attributes via sysfs is >> slow and not meant for this purpose. With IIO, you enable a scan element >> (echo 1 > in_voltage0_en) and then you enable the buffer (echo 1 > >> buffer/enable)and then you read the values from /dev/iio:device0. In the >> BB-ADC overlay, you can modify the scan update time by modifying the >> Oversample (default is 16x), Open Delay time (default is 0x98) and sample >> time (default is 1). Now the IIO ADC driver captures samples using >> interrupts which isn’t ideal, but it will capture samples at a much higher >> rate than can be read from sysfs. If you want to capture at full speed, the >> driver needs to be updated to use DMA. >> >> Regards, >> John >> >> >> >> >>> On Mar 6, 2016, at 12:19 AM, Audrey <ao...@ <>smith.edu >>> <http://smith.edu/>> wrote: >>> >>> Where can I find it (and set it)? >>> >>> I'm right now trying to collect voltage readings using beaglebone's >>> internal adc using a bash script and a while loop. Right now the data >>> collection is clocking at around 33 microseconds, but I know that the >>> internal adc should be able to collect data as fast as 5 microseconds. What >>> should I do to make that happen? Is the problem with making while loops >>> move faster, or is it about setting the adc configurations? >>> >>> This is my bash script: >>> >>> #!/bin/bash >>> >>> #echo cape-bone-iio > /sys/devices/bone_capemgr.*/slots >>> >>> t0=$(date +%s%6N) >>> >>> while true; do >>> t1=$(date +%s%6N) >>> rawVal=$(cat /sys/bus/iio/devices/iio:device0/in_voltage0_raw) >>> voltage=$(bc -l <<< $rawVal/4095*1.8) >>> time=$(expr $t1 - $t0) >>> echo $time $voltage >>> done >>> >>> >>> -- >>> For more options, visit http://beagleboard.org/discuss >>> <http://beagleboard.org/discuss> >>> --- >>> You received this message because you are subscribed to the Google Groups >>> "BeagleBoard" group. >>> To unsubscribe from this group and stop receiving emails from it, send an >>> email to beagleboard...@ <>googlegroups.com <http://googlegroups.com/>. >>> For more options, visit https://groups.google.com/d/optout >>> <https://groups.google.com/d/optout>. >> >> >> -- >> For more options, visit http://beagleboard.org/discuss >> <http://beagleboard.org/discuss> >> --- >> You received this message because you are subscribed to the Google Groups >> "BeagleBoard" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to beagleboard+unsubscr...@googlegroups.com >> <mailto:beagleboard+unsubscr...@googlegroups.com>. >> For more options, visit https://groups.google.com/d/optout >> <https://groups.google.com/d/optout>. > > > -- > For more options, visit http://beagleboard.org/discuss > <http://beagleboard.org/discuss> > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to beagleboard+unsubscr...@googlegroups.com > <mailto:beagleboard+unsubscr...@googlegroups.com>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. > > > > -- > For more options, visit http://beagleboard.org/discuss > <http://beagleboard.org/discuss> > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to beagleboard+unsubscr...@googlegroups.com > <mailto:beagleboard+unsubscr...@googlegroups.com>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. 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