The ADC module is a 200ksps SAR module . . .You're only going to be able to sample 200k samples per second . . .
Additionally you can use: 1. PRUs ( Programmable Real-time Units ) 2. IIO ( industrial IO ) 3. /dev/mem/ + mmap() To read 200ksps. Personally, I've proven that /dev/mem + mmap() can work for reading 200ksps for 7 channel simultaneously. But CPU usage is so high, that you're not going ot be able to do a whole lot more in addition to reading the ADC in this fashion. Hence, the PRU are best used, as this offers hardware offload( very little CPU load needed - and only when reading values out ). On Mon, Jun 20, 2016 at 12:00 PM, Stewart <snelson.st...@gmail.com> wrote: > I'm looking to write a simple app for BBB. When started from the command > line, it would set up the ADC in continuous mode and read ~1 M samples from > e.g. AN0 into memory. After the capture is complete, it would write the > data to a file and exit. > > Ideally, it would run at the hardware limit of 1.6 MSPS (15 cycles of 24 > MHz adc_clk per sample). If that's not practical, 800 KSPS or better would > be acceptable. > > What is an easy way to do this? Most Beaglebone ADC examples sample at > kilohertz rates or slower. > > This guide: > http://processors.wiki.ti.com/index.php/Linux_Core_ADC_User%27s_Guide > speaks of 200 KSPS. What is the limitation here? > > I've seen various suggestions to use the PRU, but don't understand why. I > would think that since DMA would be required anyway, there should be no > requirement to otherwise access the hardware with tight timing. If PRU is > indeed necessary, is there a suitable example or tutorial? (None of the > libpruio built-in examples deal with rapid sampling or large amounts of > data.) > > Any other ideas for a simple way to capture data fast will be gratefully > appreciated. > > Thanks. > > -- > 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. > To view this discussion on the web visit > https://groups.google.com/d/msgid/beagleboard/aeaf9852-fb4c-4fd1-9594-8aad0ad5fd3c%40googlegroups.com > <https://groups.google.com/d/msgid/beagleboard/aeaf9852-fb4c-4fd1-9594-8aad0ad5fd3c%40googlegroups.com?utm_medium=email&utm_source=footer> > . > 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. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CALHSORp6fi1O6wbX92umVoCWhQwOQRC2bpNKe%3DkFEQ3vBE%3D-8A%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
