> > *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?*
in_voltage0_raw == one shot mode. /dev/iio:device0 == continuous mode. continuous mode is only really useful if you need more than 3-4 thousand samples a second. Otherwise one shot mode will possibly work just fine. It really how much you're trying to do all at once. On Tue, Mar 8, 2016 at 10:51 PM, Audrey <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). > 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> 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 >> --- >> 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. >> For more options, visit 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. > To unsubscribe from this group and stop receiving emails from it, send an > email to beagleboard+unsubscr...@googlegroups.com. > For more options, visit 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. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
