Re: [Discuss-gnuradio] Remotely controlling a GNURadio flowgraph via LAN

[Albin Stigö]

You could implement your flowgraph in python and then use some python library for rpc and write a thin layer between...

You can also implement a flowgraph in C++.

I'm currently playing around with RPC over DBUS (only control, no data) for an application I'm writing in C++.

--Albin

On Fri, Aug 9, 2019, 10:35 Müller, Marcus (CEL) <address@hidden> wrote:

Hi Alex,

we do have two approaches for that

1. the XMLRPC thing, which is a python-world block that basically would
allow you to do the same you can do with e.g. a Qt GUI Range slider
(i.e. change Python variables at runtime)
2. Ctrlport and the thrift backend, the latter of which is notoriously
hard to get right.

I **really** think RPC is big in GNU Radio's future; we'll work on that
fundamentally. The problem is you're trying to solve a technical
challenge now, not then.

So, check out the XMLRPC, see if it suits you.

If it doesn't: What I'd recommend is to

1. use GRC to construct your flow graph as desired, assuming you're
doing that so far. Hint: if you use "Parameter" blocks instead of
"Variable" blocks, you get arguments to your top block's constructor)
2. Take the resulting python file, and use it as a Python module
(rather than running it as executable itself), containing a class named
like the "id" you set in the options block (the instance of
gr.top_block).
3. Write a simple application that imports that module, and modifies
the state of the top block (see the "main" function at the end of the
generated Python file) as dictated through RPC from your receiving end.

For 3: I do like zeroMQ, it has good Python integration and for your
application, the REQuest/REPly socket pattern would probably work very
well. You can encode RPC commands however you like, for example simple
JSON like {"tune", [2.4e9, 1e6]} or so.

Or, you can directly use a python RPC thing. I've not personally tried
that, but zerorpc.io looks fine for this kind of thing. Quite possible,
all you'd need to build on the Pi would be

#!/usr/bin/env python
import zerorpc
import myfg #replace with the generated .py

server = zerorpc.Server(myfg.myfg(sensible_arguments_if_any))
server.bind("tcp://0.0.0.0:1337") #bind to all interaces on port 1337

# could be tcp://127.0.0.1:1337 instead, if you're doing e.g. port
forwarding through `ssh -R 127.0.0.1:1337:1337!
# There's even ZMQ brokers and stuff, but that'd lead too far.
s.run()


And locally, you could try

import zerorpc
client = zerorpc.Client()
client.connect("tcp://yourPisAdddress:1337")
client.start()
client.set_samp_rate(4e6) #or whatever methods your top block has

Best regards,
Marcus

On Thu, 2019-08-08 at 23:16 +0100, Alex Pane wrote:
> Hi,
>
> I have created a simple tcp based iq stream using ZMQ blocks to use a HackRF remotely over an ethernet network.
>
> I have a linux computer (Raspberry Pi) connected to the HackRF running GNURadio. The HackRF source is connected to a ZMQ sink that transmits the packets to a receiving linux PC running GNURadio - where a ZMQ source connected to a QT sink for visualising the IQ signal stream.
>
> This works fine for a fixed frequency, sample rate and fft size etc, however my problem is that i want to be able to change those parameters from the receiving PC.
>
> Despite much research, i have been unable to find a way to change the parameters of the remote flowgraph (client) from the receiving display end (server).
>
> Is there a way to natively perform this operation within GNURadio and can someone provide guidance on how to setup a flowgraph to achieve this? Or is there some additional OOT block or custom python block i would need to create to do this.
>
> Thanks
>
> Alex
> _______________________________________________
> Discuss-gnuradio mailing list
> address@hidden
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