On 2/27/2019 9:35 AM, Damien.D wrote: > > Another question, regarding write to GPIO output register. I could also > measure it but do you happen to know how long does it take to write those > 4*2 (8 total) gpio set/clr register? > https://github.com/machinekit/machinekit/blob/master/src/hal/drivers/hal_pru_generic/pru_wait.p#L204-L207 > > From what I understand from: > https://github.com/machinekit/machinekit/blob/master/src/hal/drivers/hal_pru_generic/pru_generic.p#L144-L147 > each line "SBBO GState.GPIOn_CLR, State.GPIOn_CLR_ADDR, 0, 8" takes no less > than 95-105ns > > but I don't quite understand the thing that is explained about "Posted > Writes": > https://github.com/machinekit/machinekit/blob/master/src/hal/drivers/hal_pru_generic/pru_generic.p#L149-L156 > > Are those 4 SBBO "posted writes" supposedly taking 15ns each? .. or >> 95-105ns? > https://github.com/machinekit/machinekit/blob/master/src/hal/drivers/hal_pru_generic/pru_wait.p#L204-L207
The writes will happen quickly because the fabric interconnect is not saturated. Regarding "posted writes": The interconnect fabric has the ability to accept a small number of write requests immediately. The PRU can then carry on with other work while the write request makes its way through the interconnect to it's ultimate destination. https://en.wikipedia.org/wiki/Posted_write -- Charles Steinkuehler [email protected] -- website: http://www.machinekit.io blog: http://blog.machinekit.io github: https://github.com/machinekit --- You received this message because you are subscribed to the Google Groups "Machinekit" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. Visit this group at https://groups.google.com/group/machinekit. For more options, visit https://groups.google.com/d/optout.
