My mistake, I think the second link I gave is an explanation of the PRU shared memory and not DDR shared memory. So, if you do a google search for "beaglebone pru shared ddr memory" there are lots of hits out there. You're bound to find something that makes things understandable.
On Fri, Oct 14, 2016 at 8:48 AM, William Hermans <yyrk...@gmail.com> wrote: > awesome! Thank you! Do you know where I can find a good example of using >> shared memory? I am wondering if I might be better off using shared memory >> instead. Does shared memory work both ways so that ARM can access the PRU >> memory and PRU access the ARM memory? >> > > There is a DDR example here: https://github.com/beagleboard/am335x_pru_ > package/tree/master/pru_sw/example_apps/PRU_memAccess_DDR_PRUsharedRAM > > > Then if you need a better explanation of the code( Like I would ). You can > read this: http://www.embedded-things.com/bbb/understanding-bbb-pru- > shared-memory-access/ > > On Fri, Oct 14, 2016 at 4:36 AM, Jay Doobie <doobi...@gmail.com> wrote: > >> awesome! Thank you! Do you know where I can find a good example of >> using shared memory? I am wondering if I might be better off using shared >> memory instead. Does shared memory work both ways so that ARM can access >> the PRU memory and PRU access the ARM memory? >> >> >> On Thursday, October 13, 2016 at 10:59:26 PM UTC-4, Charles Steinkuehler >> wrote: >> >>> On 10/13/2016 5:48 PM, Jay Doobie wrote: >>> > Hi, >>> > >>> > I'm trying to send some data from ARM to the PRU for the PRU to >>> execute upon it, >>> > but I'm having some issues where it tends to miss some of the data on >>> the PRU, >>> > so I assume I am not synchronizing the interrupts properly, here is >>> basically >>> > what I am doing: >>> > >>> > C code: >>> > >>> > for (i = 0; i < 10; i++) { >>> > prussdrv_pru_write_memory(PRUSS0_PRU0_DATARAM, SHARED_MEMORY, >>> (unsigned >>> > int*)pkts[i], memSize); >>> > //if I put a sleep here it generally works: usleep(500000); >>> >>> The ARM has a weak memory model. You need a memory fence instruction >>> here to insure that all writes before the fence (your write to the PRU >>> memory, above) have completed before any writes after the fence >>> (generating the PRU interrupt) take effect. >>> >>> It's a bit ham-fisted, but you can use a __sync_synchronize() here >>> (assuming you're using gcc...it's a full memory barrier). Or you can >>> use the C++11 memory fence semantics (more complicated). Either is >>> way better than the "old school" full cache flush and invalidate! :) >>> >>> > //printf("sending intc...\n"); >>> > // here are the packets! >>> > prussdrv_pru_send_event(ARM_PRU0_INTERRUPT); >>> > // wait for PRU response >>> > //printf("waiting intc...\n"); >>> > prussdrv_pru_wait_event (PRU_EVTOUT_0); >>> > // clear PRU response >>> > //printf("clr intc from PRU0...\n"); >>> > prussdrv_pru_clear_event (PRU_EVTOUT_0, PRU0_ARM_INTERRUPT); >>> > >>> > } >>> > >>> > PRU: >>> > >>> > HANDLE_DATA: >>> > // wait for interrupt >>> > WBS r31, #30 >>> > // reset interrupt >>> > LBCO r20, CONST_IEP, 0x44, 4 // Load CMP_STATUS >>> register >>> > sbco rResetInterrupt, CONST_PRUSSINTC, SICR_OFFSET, 4 >>> > // handle data >>> > MOV R31.b0, PRU0_R31_VEC_VALID | PRU_EVTOUT_0 >>> > sub rCounter, rCounter, rCounter >>> > qbne HANDLE_DATA, rCounter, 0 >>> > >>> > >>> > Kernel: Linux beaglebone 3.8.13-bone79 #1 SMP Tue Oct 13 20:44:55 UTC >>> 2015 >>> > armv7l GNU/Linux >>> > >>> > Thanks! >>> >>> >>> >>> -- >>> Charles Steinkuehler >>> cha...@steinkuehler.net >>> >> -- >> 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/ms >> gid/beagleboard/ec5b24bc-3b9e-4aba-a262-f79355ce0eb4%40googlegroups.com >> <https://groups.google.com/d/msgid/beagleboard/ec5b24bc-3b9e-4aba-a262-f79355ce0eb4%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/CALHSORom%3DzmDQhbHnRc5YAhmkgRhV5mj516OYHTXO8mRQ%2B8rRw%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
