Andrew, So this is word of mouth from these very forums perhaps a couple years ago but I do recall someone ( as in someone qualified to know - don't remember exactly who ) saying that technically, GPIO's can be toggled on/off at 100-200 Mhz - Using a PRU.
Without using the PRU's . . . well the link you posted a link to in your other post was featured on HaD months ago, and is still the highest rate I've seen to date. Frankly I do not think this is a hardware limitation so much as an OS or software limitation. So no way really to generically document that in the hardware specs. Another thing to keep in mind is that the AM335x processors are generic purpose processors, where many / all M0, M0+, M3/M4 are more specific purpose. Geared towards doing a few things very well, and fast. Anyway, if you need more speed, perhaps an RTOS or even just tightening up the Linux "message pump" ( e.g. RT kernel ) might prove helpful ? On Mon, Aug 24, 2015 at 4:12 PM, Andrew P. Lentvorski <bsd...@gmail.com> wrote: > I've been trying to hunt down the maximum frequency on the BeagleBone > Black GPIO pins. > > This *seems* to be dominated by the transaction latency across the L3/L4 > interconnect. Fair enough. So ... > > > What's the latency number? > > > I've *measured* about 166ns per transaction (I can create a roughly 3MHz > toggle which is 2 pin flips which requires 6MTransactions/s which is > 166.66ns per transaction). But I don't know how to *calculate* that number > from the documentation. > > I've been through the TI reference manuals, the TI support forums, and a > bunch of other things, but *nobody* seems to be able to cough up an actual > number for this. > > Anybody have some references to frequencies and bus wait numbers? They > may be out there, but GTMF/RTFM doesn't seem to be sufficient. > > I don't need turbo speed, but the fact that it's entirely possible that I > may not even be able run at 1MHz (something *painfully* easy for most M0 or > M3/M4 cores) is, frankly, a bit of a shock. > > 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. > 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.
