If you want a GPIO to trigger a transmission, then to my knowledge, it is not possible with software in the loop (assuming the requirement is sub-ms latency).
There is a hacky way to do it, which is to hook up your external GPIO trigger to the PPS input of the X300 ( https://lists.gnu.org/archive/html/discuss-gnuradio/2015-09/msg00010.html) If you want external events to trigger radio transmission/reception behavior, you'll have to mess with the FPGA code. Best, Raghav On Thu, Dec 8, 2022 at 9:48 AM Jeff S <[email protected]> wrote: > Raghav, > > > > I was looking into timed commands for the outputs, but how do you time the > input to GPIO and cause the timed outputs to wait for the input to be > active? > > > > Regards, > > Jeff > > > > *From:* Raghav Subbaraman <[email protected]> > *Sent:* Thursday, December 8, 2022 11:41 AM > *To:* Jeff S <[email protected]> > *Cc:* [email protected] > *Subject:* Re: [USRP-users] X310 GPIO Latency > > > > Hi Jeff, > > > > We have used Timed commands to control the GPIO set/unset timing > accurately (UHD 4.1.5 + GNURadio 3.8.2). We have seen that the GPIOs can be > controlled with 10s of ns of accuracy in the X310. > > > > Best, > > Raghav > > > > On Thu, Dec 8, 2022 at 3:34 AM Jeff S <[email protected]> wrote: > > I’ve been working on a software keying loop with the GPIO on an X310, and > I measured the latency for setting a GPIO pin output wrapped back into a > GPIO input to be around 5 ms on average. This was done by setting a pin > manually, and then immediately polling the input pin to see how long before > it switched states. > > > > I haven’t had anyone who could look at the FPGA side of the X310 yet, but > I was wondering if it would be even possible to implement something in the > FPGA like the ATR functionality, except it would allow for a keying loop (a > Clear to Send GPIO output wrapping to a Request to Send GPIO input) and > prevent transmission until the condition was true. I’m hoping that would > significantly decrease the latency (less than 1 ms, hopefully) if I don’t > have to bother polling the pin. > > > > Right now I’m using: UHD 4.0, and GNU Radio 3.9.5. > > > > Thanks and regards, > > Jeff > > > > _______________________________________________ > USRP-users mailing list -- [email protected] > To unsubscribe send an email to [email protected] > > > > > -- > > Raghav Subbaraman > > PhD Student, ECE > > University of California San Diego > > rsubbaraman.github.io > -- Raghav Subbaraman PhD Student, ECE University of California San Diego rsubbaraman.github.io
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