Test with message_source

GNU Radio
1

Hi,

I am trying to understand how the message source works
and how I can use it from within my python code.
So I wrote a simple script with a message source and a null sink.
I wanted the following behavior:
every time I press a button on my keybord to send a constant message in
the queue and verify that the queue size has increased.

Here is the piece of code that I have so far…

What I don’t know how to do is to enqueue a message every time
I press a button.
Can someone point to the right direction as to how this event driven
behavior is implemented.

Thanks
Achilleas

==========================================================
from gnuradio import gr
from gnuradio import audio
from gnuradio.eng_option import eng_option
from optparse import OptionParser

class my_graph(gr.flow_graph):

 def __init__(self):
     gr.flow_graph.__init__(self)

     packet = 'abcdefghijklmnopqrstuwxy' #multiple of

gr.sizeof_float
msg=gr.message_from_string(packet)

     src0 = gr.message_source(gr.sizeof_float,10)
     dst = gr.null_sink (gr.sizeof_float)
     self.connect (src0, dst)

     # Now I want every time I press a button to run the following

code,
# so that I add the same msg in the message queue
src0.msgq().insert_tail(msg)
print src0.msgq().count()

if name == ‘main’:
try:
my_graph().run()
except KeyboardInterrupt:
pass

2

Anastasopoulos Achilleas wrote:

What I don’t know how to do is to enqueue a message every time
I press a button.
Can someone point to the right direction as to how this event driven
behavior is implemented.

Look in the gnuradio-examples/python/digital/tunnel.py and subfiles.

transmit_path.py has a send_pkt function which calls the send_pkt
function in pkt.py (in the gnuradio python libraries directory), which
converts a string into the proper format and enqueues it into a message
queue.

When you’re done with the queue, and you want to close up, call the
send_pkt function with eof = True (enqueues gr.message(1)), which tells
the queue that no more input is coming and enables the fg to stop.

-Dan