Andy, there are two kinds of PRU GPIO writes, the direct ones, in which you write to the R30 register, and ones where you have to access the gpio subsystem, you only need to mux it to the PRU if you're doing the direct method.
On Monday, January 12, 2015 at 9:07:17 AM UTC-8, AndyS wrote: > > Thank you for your quick replies. I will work through the examples this > evening. > > Ok. I think I might be getting a little confused of something called mux > mode5 which looks like it is specific to an example I have been following > on GPIO from Derek Molloy. > > Can I create my own overlays to configure the mux which uses both GPIO and > PRU IO? ( and the ADC if required) > > > > On Monday, January 12, 2015 at 4:57:19 PM UTC, Charles Steinkuehler wrote: >> >> On 1/12/2015 5:11 AM, AndyS wrote: >> > Hello, >> > >> > I have an application which requires use of the PRU for some fast IO. >> I >> > need to use more IO than the PRU can handle, but some of the other IO >> only >> > needs to operate in slow time. >> > >> > Can I configure the BBB to use both PRU IO and Linux controlled GPIO. >> >> Yes. The PRU writes to GPIO pins are not particularly slow unless you >> saturate the interconnect, but the writes are posted and happen a while >> after the PRU executes them (apx. 100 nS later). Unless you need >> critical timings between the direct PRU outputs and the GPIO pins, this >> shouldn't be a problem. >> >> Reads from GPIO pins are another matter. Since it is not possible to >> post the reads, and the PRU (by design) doesn't execute instructions out >> of order or perform speculative execution, the PRU core stalls after >> issuing a read GPIO request until the data is returned from the >> interconnect fabric (apx. 165 nS). >> >> I have timing details in the comments of my PRU code for Machinekit: >> >> >> https://github.com/machinekit/machinekit/blob/master/src/hal/drivers/hal_pru_generic/pru_generic.p#L135-L163 >> >> >> -- >> Charles Steinkuehler >> [email protected] >> > -- 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/d/optout.
