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-boun...@lists.ettus.com> on behalf of Thomas Harder via USRP-users <usrp-users@lists.ettus.com> Sent: Tuesday, January 14, 2020 5:07 AM To: usrp-users@lists.ettus.com <usrp-users@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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