Re: [Discuss-gnuradio] issue about message port of grextras

[Tom Rondeau]

On Thu, Apr 24, 2014 at 12:01 AM, Damon <address@hidden> wrote:

Hi Tom,

Thanks for you reply.

I am wondering why the data stream ports of byte or integer 8 could be disconnected by other ports.

Here is an example. The connecting code is commented out, but we can run this program without getting a error.

#!/usr/bin/env python

##################################################

# Gnuradio Python Flow Graph

# Title: Top Block

# Generated: Thu Apr 24 11:57:08 2014

##################################################

from gnuradio import blocks

from gnuradio import eng_notation

from gnuradio import gr

from gnuradio.eng_option import eng_option

from gnuradio.filter import firdes

from optparse import OptionParser

class top_block(gr.top_block):

    def __init__(self):

        gr.top_block.__init__(self, "Top Block")

        ##################################################

        # Variables

        ##################################################

        self.samp_rate = samp_rate = 32000

        ##################################################

        # Blocks

        ##################################################

        self.blocks_null_source_0 = blocks.null_source(gr.sizeof_char*1)

        self.blocks_null_sink_0 = blocks.null_sink(gr.sizeof_char*1)

        ##################################################

        # Connections

        ##################################################

        #self.connect((self.blocks_null_source_0, 0), (self.blocks_null_sink_0, 0))

# QT sink close method reimplementation

    def get_samp_rate(self):

        return self.samp_rate

    def set_samp_rate(self, samp_rate):

        self.samp_rate = samp_rate

if __name__ == '__main__':

    parser = OptionParser(option_class=eng_option, usage="%prog: [options]")

    (options, args) = parser.parse_args()

    tb = top_block()

    tb.start()

    raw_input('Press Enter to quit: ')

    tb.stop()

    tb.wait()

Best regards,

Damon

I really don't understand the question. Why do you think this behavior is wrong? There are no blocks in the flowgraph; that's not a condition to say it won't run. When you hit start, it'll try to start all threads; there are none, so it will immediately exit. The raw_input is a Python thing, so that will continue to block.

Tom

 

2014-04-23 21:46 GMT+08:00 Tom Rondeau <address@hidden>:

On Tue, Apr 22, 2014 at 5:09 AM, Damon <address@hidden> wrote:

Hi all,

Recently I am learning the grextras project. I am confused about the
message port which is designed in grextras.
Why will we not get a error when the message ports do not connect to
other message ports? I thought those port actually is data stream ports,
so they should be connected to other ports.

Best regards,
Damon

Damon,

grextras is an external project from GNU Radio and not related to the core functionality.

But GNU Radio's message passing structure does not require connections. It's a publish-subscribe model, and a block will publish a message regardless of whether or not another block is subscribed and listening.

Tom