|Subject:||Re: [Discuss-gnuradio] Message API questions|
|Date:||Wed, 26 Feb 2014 14:26:24 +0000|
From: Aditya Dhananjay [mailto:address@hidden
On Wed, Feb 26, 2014 at 8:45 AM, Nowlan, Sean <address@hidden> wrote:
I have a few questions regarding messages in GR.
1) Is it possible to mix-and-match the old style message sink/source blocks with the new style message passing API? Any guidance on how to make the connections? I didn’t have much luck with msg_connect. I don’t think the message sink/source blocks have an associated port name to make this possible. Perhaps that’s something worth adding internally?
I'm not sure I completely understand your question.
Have you looked at the OFDM Tx/Rx examples in PATH/gr-digital/examples/ofdm? The flowgraph is a combination of standard connections within blocks, along with a message passing connection (look at the header/payload demux block).
Thanks! What I was referring to are the gr::blocks::message_source and gr::blocks::message_sink blocks. They don’t use the new style message passing API in which you register ports and message handlers. Instead, gr::blocks::message_source has an internal message queue. It blocks in within its work function waiting for a message to enter the queue. What I’m wondering is how to connect a new style block’s message output with the input to this block, and the inverse case for connecting a gr::blocks::message_sink to a new style block’s message input.
Are you using actual hardware or is this a software only simulation?
I basically have flowgraph (FG1) --> message domain --> flowgraph (FG2) --> USRP. FG1’s flow rate is not constrained by streaming backpressure. FG2’s flow rate is constrained by the USRP. To constrain FG1’s flow rate I either have to use a throttle block or find a way to enforce flow control in the message domain.
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