[USRP-users] GPIO with X310

Marcus D. Leech mleech at ripnet.com
Thu Dec 4 16:28:45 EST 2014

On 12/04/2014 04:24 PM, Andy Walls wrote:
> /me holsters gun
> (I don't know what "COR" means.)
Carrier-Operated Relay.   Basically, a directional 

> The UHD API does let one map any set of the 4 ATR indicators to the GPIO
> pin, so it's not a big problem, just a "gotcha".  The logic gets fun
> when you need an active low transmit GPIO output regardless of receive.
> (Left as an exercise for the reader.)
> Regards,
> Andy
>>>>     Since there are two channels, does it mean transmit on either
>>>> channel?  I don't see a way to specify this behavior as a function of
>>>> the transmit channel.
>>> Good question.   Looking at the FPGA source code, it looks like the
>>> Front Panel GPIO is propagated up from radio 0 (the first daughter card)
>>> and not at all from radio 1 (the second daughter card).
>>> Obviously a quick test with a DVM or oscilloscope can be used to verify
>>> that.
>>>> 2) I am not looking for really precise accuracy (really, about 1 msec
>>>> is good enough), but I would like for this transmit bit rising edge to
>>>> occur at the same time as the RF signal appears at the SMA connector.
>>>> Does this seem possible?  If not, perhaps there would at least be a
>>>> "fixed" delay between the onset of the transmit bit and the RF?
>>> Another good question.  I can't help here.
>>>> 3) I see how this is called from C++ using set_gpio_attr.  However, I
>>>> would like to do this from GNU radio.  Is this possible?  Are there
>>>> any examples?
>>> There is no existing GNURadio block.  I had to write my own block for
>>> GNURadio and GRC.  It is possible.
>>> Regards,
>>> Andy
>>> _______________________________________________
>>> USRP-users mailing list
>>> USRP-users at lists.ettus.com
>>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com

Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium

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