Re: Monitor O's and U's from Python

[Marcus Müller]

Hi Richard and Marcus,

We managed to do it: Now I'm confused!

So, as expected, things like

from gnuradio.blocks import message_debug
blk = message_debug()
print(blk.message_ports_in())
#(print_pdu store print system)

work quite nicely.

However, um, that's not the case for

from gnuradio import uhd
src = "" uhd.stream_args_t(cpu_format="fc32", channels=(0,)))
print(src.message_ports_out())
#()

although I can very much see the code that should be adding the port in the commit I mentioned last email. Or so I thought.

That just adds the port to the USRP sink. So, I was wrong, and ph1t0's commit cb27b1f496 added that same port to the source only in later 2022, and that wasn't backported to maint-3.10.

OK, Richard, change of plans: Before the USRP block(s) had that message port, we all just used the "UHD: USRP Async Msg Source" block, which, as you might guess, fulfills that role. I think it might not work in GRC in 3.10, but it's probably the way to go on 3.8. Haven't worked with it in quite a while, but if you have the uhd_rx_cfile example at hand: that shows how to use it in Python.

Hope this is a at least a bit helpful, and sorry for the confusion,

Best,
Marcus

On 23.04.23 11:54, Marcus Müller wrote:

Hi Richard, hi Marcus,

huh, surprising; Piotr Krysik's commit 94fddb6371264c79969c0448c19fdb637d6ffc31 added these in 2018, back in the days when we've had tagged 3.8tech-preview. So, that *really* should be in there. Let me quickly spin up a retro machine with 3.8 on it and check that.

Best,

Marcus

On 23.04.23 03:33, Marcus D. Leech wrote:

On 22/04/2023 21:25, Richard Bell wrote:

Thanks for catching that Marcus. 

I'm still having a problem even finding an output message port for the usrp_source block. I should say I'm using gnuradio 3.8.5, if that makes a difference.

For example, if I print self.uhd_usrp_source.message_ports_in() I get "command" and "system". But if I print self.uhd_usrp_source.message_ports_out() I get an empty tuple.Are output message ports on usrp sources somewhat new?

They must be really new, because I'm running GR 3.10 with UHD 4.1.0.5 and there's no output message port.

On Sat, Apr 22, 2023 at 7:07 AM Marcus D. Leech <patchvonbraun@gmail.com> wrote:

On 22/04/2023 01:46, Richard Bell wrote:

Hi Marcus,

Good to hear from you, I hope all is well. Thanks for this response.

I tried doing what you said, but I get the attached error message. I have been looking the docs but haven't found much discussion that is helping. Do you see anything wrong with these relevant code snippets?

# create the USRP source

self.uhd_usrp_source_0 = uhd.usrp_source(
            ",".join((addr0, "", "master_clock_rate=200e6")),
            uhd.stream_args(
                cpu_format="fc32",
                args='',
                channels=list(range(0,1)),
     ),
)

# create the message debug block

self.message_debug_block = blocks.message_debug()

# connect the usrps async_msgs port to the message debug blocks store port

self.connect((self.uhd_usrp_source, 'async_msgs'), (self.message_debug_block, 'store'))

I think you should be using msg_connect, rather than "connect".