Hi everyone,
I'm trying to replicate a GNU Radio flowgraph and run it directly in UHD 4.0
using C++, but I'm running into an issue that I can't solve.
The Python/GNU Radio version works perfectly, but the equivalent C++
implementation fails at runtime with the following error:
RuntimeError: AccessError: Attempting to read property
\`samp_rate@INPUT_EDGE:0' before it was initialized!
I already tried configuring the DDC and DUC after the commit, but the problem
still persists and I don't understand why this property is not being
initialized correctly.
The RFNoC graph topology is the following:
0/SEP#0:0==>0/DUC#0:0
| | \* 0/DUC#0:0==>0/Radio#0:0
| | \* 0/Radio#0:0==>0/DDC#0:0
| | \* 0/DDC#0:0==>0/SEP#0:0
| | \* 0/SEP#1:0==>0/DUC#0:1
| | \* 0/SEP#4:0==>0/Block#0:0
| | \* 0/Block#0:0==>0/SEP#4:0
>From what I understand, the issue seems related to the propagation or
>initialization order of the samp_rate property across the graph edges, but I’m
>not sure which block is responsible or how GNU Radio handles this internally
>compared to UHD C++.
Below are the working GNU Radio/Python implementation and the failing UHD C++
implementation:
**Python / GNU Radio code (working)**
`# Blocks`
` ##################################################`
` self.ettus_rfnoc_tx_radio_0 = ettus.rfnoc_tx_radio(self.rfnoc_graph,
uhd.device_addr(''),`
` -1,`
` -1)`
` self.ettus_rfnoc_tx_radio_0.set_rate(samp_rate)`
` self.ettus_rfnoc_tx_radio_0.set_antenna('TX/RX', 0)`
`
self.ettus_rfnoc_tx_radio_0.set_frequency(uhd.tune_request(center_freq_out,
((samp_rate*0.5) + 2e6)), 0)`
` self.ettus_rfnoc_tx_radio_0.set_gain(0, 0)`
` self.ettus_rfnoc_tx_radio_0.set_bandwidth(samp_rate, 0)`
` self.ettus_rfnoc_rx_radio_0 = ettus.rfnoc_rx_radio(`
` self.rfnoc_graph,`
` uhd.device_addr("spp=16"),`
` -1,`
` -1)`
` self.ettus_rfnoc_rx_radio_0.set_rate(samp_rate)`
` self.ettus_rfnoc_rx_radio_0.set_antenna('RX2', 0)`
` self.ettus_rfnoc_rx_radio_0.set_frequency(center_freq_in, 0)`
` self.ettus_rfnoc_rx_radio_0.set_gain(55, 0)`
` self.ettus_rfnoc_rx_radio_0.set_agc(False, 0)`
` self.ettus_rfnoc_rx_radio_0.set_bandwidth(samp_rate, 0)`
` self.ettus_rfnoc_rx_radio_0.set_dc_offset(True, 0)`
` self.ettus_rfnoc_rx_radio_0.set_iq_balance(True, 0)`
` self.ettus_rfnoc_duc_0 = ettus.rfnoc_duc(`
` self.rfnoc_graph,`
` uhd.device_addr(''),`
` -1,`
` -1)`
` self.ettus_rfnoc_duc_0.set_freq(0, 0)`
` self.ettus_rfnoc_duc_0.set_input_rate(samp_rate, 0)`
` self.ettus_rfnoc_ddc_0 = ettus.rfnoc_ddc(`
` self.rfnoc_graph,`
` uhd.device_addr(''),`
` -1,`
` -1)`
` self.ettus_rfnoc_ddc_0.set_freq(0, 0)`
` self.ettus_rfnoc_ddc_0.set_output_rate(samp_rate, 0)`
` self.Filter_Passtaps_Filter_Passtaps_0 =
Filter_Passtaps.Filter_Passtaps(`
` self.rfnoc_graph,`
` uhd.device_addr(''),`
` -1,`
` -1)`
` self.Filter_Passtaps_Filter_Passtaps_0.set_int_property('user_reg', 0)`
` self.Filter_Passtaps_Filter_Passtaps_0.set_int_property('user1_reg',
66)`
` self.Filter_Passtaps_Filter_Passtaps_0.set_int_property('user2_reg',
-2)`
` self.Filter_Passtaps_Filter_Passtaps_0.set_int_property('user3_reg',
0)`
` `
` `
` ##################################################`
` # Connections`
` ##################################################`
`
self.rfnoc_graph.connect(self.Filter_Passtaps_Filter_Passtaps_0.get_unique_id(),
0, self.ettus_rfnoc_duc_0.get_unique_id(), 0,
self.rfnoc_graph.skip_propagation)`
` self.rfnoc_graph.connect(self.ettus_rfnoc_ddc_0.get_unique_id(), 0,
self.Filter_Passtaps_Filter_Passtaps_0.get_unique_id(), 0,
self.rfnoc_graph.skip_propagation)`
` self.rfnoc_graph.connect(self.ettus_rfnoc_duc_0.get_unique_id(), 0,
self.ettus_rfnoc_tx_radio_0.get_unique_id(), 0,
self.rfnoc_graph.skip_propagation)`
` self.rfnoc_graph.connect(self.ettus_rfnoc_rx_radio_0.get_unique_id(),
0, self.ettus_rfnoc_ddc_0.get_unique_id(), 0,
self.rfnoc_graph.skip_propagation)`
**UHD C++ code (failing)**
`uhd::rfnoc::block_id_t rx_radio_id("0/Radio#0");`
` uhd::rfnoc::block_id_t tx_radio_id("0/Radio#0");`
` `
` const size_t rx_chan = 0; // RX2 normalmente`
` const size_t tx_chan = 0; // TX/RX normalmente`
` `
` uhd::rfnoc::block_id_t ddc_id("0/DDC#0");`
` uhd::rfnoc::block_id_t duc_id("0/DUC#0");`
` `
` uhd::rfnoc::block_id_t filter_id("0/FilterPasstaps#0");`
` /**********************************************************************`
` * GET BLOCK HANDLES`
` *********************************************************************/`
` auto rx_radio =
graph->get_block<uhd::rfnoc::radio_control>(rx_radio_id);`
` auto tx_radio =
graph->get_block<uhd::rfnoc::radio_control>(tx_radio_id);`
` auto ddc = graph->get_block<uhd::rfnoc::ddc_block_control>(ddc_id);`
` auto duc = graph->get_block<uhd::rfnoc::duc_block_control>(duc_id);`
` auto filter =
graph->get_block<uhd::rfnoc::FilterPASStaps_block_ctrl>( filt_id );`\
\
\
`// Configurations Radio RX and TX, DUC and DDC. `\
\
` `
` graph->connect(rx_radio_id, rx_chan, ddc_id, 0, true);`
` graph->connect(ddc_id, 0, filter_id, 0, true);`
` graph->connect(filter_id, 0, duc_id, 0, true);`
` graph->connect(duc_id, 0, tx_radio_id, tx_chan, true);`
` std::cout << "Commit graph..." << std::endl;`
` graph->commit();`
Has anyone encountered something similar or knows the correct
initialization/configuration order for RFNoC DUC/DDC blocks in UHD 4.0 C++?
Any help would be greatly appreciated.\
\
Thanks in advance!!
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