You should read the info Steward provided. There is a conflict in the AM3358 datasheet because it does say max 200ksps, but in the register settings, it does show you can configure the ADC for 1.6msps. There are discussions on E2E about this issue and no one from TI has said you cannot achieve 1.6msps.
Regards, John > On Jun 20, 2016, at 2:53 PM, William Hermans <[email protected]> wrote: > > 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: > > PRUs ( Programmable Real-time Units ) > IIO ( industrial IO ) > /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 <[email protected] > <mailto:[email protected]>> 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 > <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 > <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 [email protected] > <mailto:[email protected]>. > 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 > <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 [email protected] > <mailto:[email protected]>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/beagleboard/CALHSORp6fi1O6wbX92umVoCWhQwOQRC2bpNKe%3DkFEQ3vBE%3D-8A%40mail.gmail.com > > <https://groups.google.com/d/msgid/beagleboard/CALHSORp6fi1O6wbX92umVoCWhQwOQRC2bpNKe%3DkFEQ3vBE%3D-8A%40mail.gmail.com?utm_medium=email&utm_source=footer>. > 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. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CDE96EC4-4C68-4022-9390-7F5011F12FB5%40gmail.com. For more options, visit https://groups.google.com/d/optout.
