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.
