Tim, you can attach a stream tag to the sample on which the GPIO should go high or low. The tag key should be "tx_command". The PMT format is the same as if you were sending a message to the block. Tags get processed first (before samples). That does mean that you need write to a block that checks if you are silent or not, and adds the tags.
Careful if you are sending too many commands. You could stall your transmit pipeline, causing underruns. In that case, modifying the FPGA might be required. Or, you could send your data as bursts to the USRP sink (using the end of burst feature) and then have the GPIO pin track the ATR state (i.e., you don't send the zeros). --M On Thu, Oct 24, 2024 at 3:29 PM Tim Vancauwenbergh < tim.vancauwenberg...@gmail.com> wrote: > Hello, > > I have a GRC flow which generates a series of pulses. To suppress the LO > leakage from the transmitter being on while sending samples with value '0' > I want to use a method in GNU Radio Companion to Toggle a GPIO pin. > The pulses are always the same, but I cannot use repetition using RFNoC as > the *B200 mini *which is used for this project does not support that. > Whenever the sample values for transmission are greater than 0, the GPIO > pin should be high, otherwise it should be low. > > Question being: > *How can I synchronize the flow of samples with the triggering of the GPIO > in GRC?* > > I have a script using UHD to toggle the GPIO pins using timed commands, > which works great. However, when using GNU Radio Companion, I am obliged to > use the USRP sink block. It does have a command input port, but I don't > know how to sync the commands with the sample flow. If there are other, > more straight forward methods I am happy to know. > I should maintain the functionality of transmitting the samples from GRC, > as I compare them later on with a second stream of samples. > > Thank you for your time. > > Best regards, > > Tim Vancauwenbergh > _______________________________________________ > USRP-users mailing list -- usrp-users@lists.ettus.com > To unsubscribe send an email to usrp-users-le...@lists.ettus.com >
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