[USRP-users] using GPIO output to trigger external RF switches

Sam Reiter sam.reiter at ettus.com
Tue Jan 14 12:44:27 EST 2020


Thomas,

To accomplish what you're talking about, I think you'd just need to use
timed commands on both set_tx_rate() and set_gpio_attr(). If these are set
to execute simultaneously, the GPIO line you set will go high on the same
clock cycle as the LO retune.

Sam


On Tue, Jan 14, 2020 at 5:59 AM Jeff S via USRP-users <
usrp-users at lists.ettus.com> wrote:

> Thomas,
>
> I am looking at GPIO right now as well.  As to your question #2 on
> examples, I compiled and am able to run the example I found in the UHD
> software:
>
> uhd/host/examples/gpio.cpp
>
>
> I am able to set individual data lines to experiment with (and eventually
> use as a roadmap for my development) using commands like:
>
> ./gpio --dwell 0 --bitbang --ddr 0x00ff --out 0x0055
>
>
> which I verified works using a logic analyzer.  I eventually want to try
> to create a keying loop, but that may take some FPGA control (?).
>
> Jeff
>
>
> ------------------------------
> *From:* USRP-users <usrp-users-bounces at lists.ettus.com> on behalf of
> Thomas Harder via USRP-users <usrp-users at lists.ettus.com>
> *Sent:* Tuesday, January 14, 2020 5:07 AM
> *To:* usrp-users at lists.ettus.com <usrp-users at lists.ettus.com>
> *Subject:* [USRP-users] using GPIO output to trigger external RF switches
>
>
> Hi,
>
> I am continuously transmitting a waveform with several RF with 200MSPS
> with my USRP X310 (modified code on the basis of “tx_samples_from_file.cpp”
> with a waveform in a .dat file). I would like to get a trigger signal from
> the USRP when it is changing the tx- frequency which I set in my .dat file.
>
> Could the GPIO deliver this trigger without changing the image?
>
> I am using the SRAM image with UHD 3.14.1
>
>
>
> A second question is concerning the GPIO example on
> https://files.ettus.com/manual/page_gpio_api.html.
>
> I copied and paced it in the “tx_waveforms” example just changing the usrp
> device handle to “usrp” but when I compiled it and started tx, I couldn’t
> measure any tension on PIN 4 and 6 as defined in the example. Are there
> more examples how to program the GPIO?
>
> Thank you,
>
> Thomas
> _______________________________________________
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> USRP-users at lists.ettus.com
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>
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