On Thu, Nov 21, 2013 at 10:49 PM, Charles Steinkuehler <[email protected]> wrote: > On 11/20/2013 9:30 AM, Ozan Çağlayan wrote: >> I enabled the virtual PRU cape using device tree overlay and >> successfully compiled and launched the blink code I found on the >> internet but I'm quite confused in finding out which GPIO pins are >> accessible/available from PRU. There are a lot of documents, specs, >> pin names, gpio offsets, pinmuxes, etc. Do I need to apply a dtbo for >> having 2xGPIO or are there already available ones that the PRU can >> access? > > The PRU can control all GPIO pins, just write directly to the set and > clear registers.
So are the pr_pru[01]_* modes for some pins are just for faster GPI/GPO access? > > There are many ways to create a delay. The easiest would just be a > software loop, or you can use the IEP timer documented in the latest PRU > reference manual, or many other options. More detail about exactly what > you're trying to do, what you've tried, and your design constraints will > probably get you more useful help. Thanks for the pointers. A timer will be much easy if it is easy to implement :) What I'm trying to do is to flicker 2 LEDs with different flickering rates, say 15Hz and 18Hz or 18Hz and 19Hz (but not much than ~25Hz). A userspace code will trigger this flickering and do another stuff. Once it decides to stop the flickerings, it will notify the PRU and the PRU will stop flickering/driving the LEDs. But after some while the userspace code may again decide to start flickering. So one possibility is to launch and terminate the firmware each time but I don't know if loading the firmware and executing it has a big overhead or not. Another is to use some busy waiting in the firmware so that the code just does nothing unless the userspace code tells him to start flickering. I don't know which one is easier though. Thanks again. -- Ozan Çağlayan Research Assistant Galatasaray University - Computer Engineering Dept. http://www.ozancaglayan.com -- 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]. For more options, visit https://groups.google.com/groups/opt_out.
