First I should give some context on my project. What we are trying to build
is a python server that utilizes gnuradio's blocks to get information from
hardware and send it outbound, as well as receiving requests from clients
to the server about configuration of flowgraph. More specifically, right
now, I have:
Oscom Source -->Log Power FFT --> Vector Probe
For simplicity, I am using the RTL-SDR for testing purposes. In the future,
we will be using our own device driver created within the SoapySDR
framework, hence why we are using the oscom block.
The problem starts with the fact that this may not be the only flowgraph we
utilize. The hardware we are using may start pumping out FFT values instead
of IQ values. Which means we would need a flowgraph that looks more like:
Oscom Source --> Vector Probe
(Ignore the fact that this is not possible with the oscom block currently,
we will cross that bridge in the future)
So I need to be able to stop my current running flowgraph, and start a new
one. This is where I run into trouble. I can stop my flowgraph perfectly
fine with:
flowgraph.stop()
flowgraph.wait()
time.sleep(5)
But I would like to keep the variable the same in my python code even when
I change the flowgraph. So I try:
flowgraph = newFlowgraphConstructor()
But this causes a python error at the flowgraph.stop() line: "variable
mentioned before instantiated"
To get around this, I made a resetFlowgraph function:
def resetFlowgraph():
flowgraph = newFlowgraphConstructor()
flowgraph.start()
and call things in this order:
flowgraph.stop()
flowgraph.wait()
time.sleep(5)
resetFlowgraph()
The flowgraph starts successfully, but fails to "claim" the RTL-SDR from
the old flowgraph. I have also tried the same with only my device plugged
in, and a similar problem occurs. Is there a way to force the flowgraph to
relinquish its hold on the hardware? Our python server code needs to
continue running, so I need to be able to do this restart without ending
the program (The idea is to have the server always be running and not be
manned most of the time).
Here's some pseudo code to give you an idea of how the code is structured:
#First I have a premade object generated from gnuradio-companion
#I import that object into my server code
import flowgraphInit from flowgraph
#I can also import my other flowgraph
import newFlowgraphConstructor from flowgraph2
#At global level
flowgraph = flowgraphInit()
flowgraph.start()
class ClientSocketConnection
...#init and other functions
def onMessage(payload):
#Parse message
#If we need to change to a different flowgraph
flowgraph.stop()
flowgraph.wait()
time.sleep(5)
resetFlowgraph()
def resetFlowgraph():
flowgraph = newFlowgraphConstructor()
flowgraph.start()
def main():
#create socket factory so we can allow many connections
#So there is only one flowgraph, but many people can see it and
potentially change it
(I have seen this question asked before here
https://lists.gnu.org/archive/html/discuss-gnuradio/2014-01/msg00411.html
but there was no solution in the thread)
Any help is appreciated!
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