Dear Dexter, you can of course implement your own gain_impl for GR integration, but why would you do that if there is a generic implementation provided by GR that get's the job done? Have a look at my original reply on the mailing list again (cited below): There I described how I instantiate a generic RFNoC block from gr-uhd/lib (uhd.rfnoc_block_generic <https://github.com/gnuradio/gnuradio/blob/2e59108989fb8e06a54abee0f23cba33827e0b2f/gr-uhd/lib/rfnoc_block_generic_impl.h>) instead of a custom gain block implementation in gr-oot/lib; and use the concept of user properties to pass parameters. Properties are a very powerful and useful concept in RFNoC, not only to handle sampling rate changes (|PROP_KEY_SAMP_RATE|) but for any user parameter. This is also the mechanism most of the default blocks in gr-uhd use <https://github.com/search?q=repo%3Agnuradio%2Fgnuradio+rfnoc_block_generic+language%3AYAML&type=code&l=YAML>. How does it connect to the FPGA? The third parameter of uhd.rfnoc_block_generic is the block name ("Gain"), and in the very bottom of gain_block_control.cpp <https://git.gsi.de/p.niedermayer/exciter/-/blob/cf444ed055274ec826bc0956eed0b94debbab912/rfnoc-beam_exciter/lib/gain_block_control.cpp#L63-64> the macro |UHD_RFNOC_BLOCK_REGISTER_DIRECT| is used to tell UHD, that a block with name "Gain" should use this block controller to connect to a certain NoC-ID. In the block controller you can then handles properties and pokes registers. Kind regards Philipp > Generally, I found that using "|uhd.rfnoc_block_generic|" in > combination with properties makes things a lot easier regarding > bindings, since it means you need much less code and no custom Python > bindings. > > In my_rfnoc_gain.block.yml > <https://git.gsi.de/p.niedermayer/exciter/-/blob/cf444ed055274ec826bc0956eed0b94debbab912/rfnoc-beam_exciter/grc/beam_exciter_rfnoc_gain.block.yml>: > > templates: > imports:|- > from gnuradio import uhd > make:|- > uhd.rfnoc_block_generic( > self.rfnoc_graph, > uhd.device_addr(""), > "Gain", > -1, # device_select > -1, # instance_index > ) > self.${id}.set_property('gain', ${constant}) > callbacks: > -set_property('gain',${constant}) > > And in gain_block_control.cpp > <https://git.gsi.de/p.niedermayer/exciter/-/blob/cf444ed055274ec826bc0956eed0b94debbab912/rfnoc-beam_exciter/lib/gain_block_control.cpp> > > |property_t<int> _prop_gain = property_t<int>(PROP_GAIN, DEFAULT_GAIN, > {res_source_info::USER});| > > void_register_props(){ > register_property(&_prop_gain); > add_property_resolver({&_prop_gain}, {&_prop_gain}, [this](){ > this->set_gain_value(this->_prop_gain.get()); > }); > } RFNOC_BLOCK_CONSTRUCTOR(gain_block_control){ > _register_props(); > } > > voidset_gain_value(constintgain){ > //The gain block fromthe tutorial only supports integer gain values > regs().poke32(REG_GAIN, (uint32_t)gain); > } > intget_gain_value(){ > returnregs().peek32(REG_GAIN); > } > > UHD_RFNOC_BLOCK_REGISTER_DIRECT(gain_block_control, 0xb16, "Gain", > CLOCK_KEY_GRAPH, "bus_clk") > > ------------------------------------------------------------------------ *From:* Dexter Lee [mailto:Dexter.Lee@Millennium-Space.com] *Date:* Wednesday, June 19, 2024 at 01:16 UTC+2 *Subject:* [USRP-users] Re: Building OOT RFNoC modules for GNURadio 3.10 > Hi Phillip, > > Thank you for your post regarding the gain example for UHD 4 in the > absence of RFNOCMODTOOL.  I have been frustrated with this lately and > your repo was immensely helpful. > > One question I had was how you were able to create the RFNOC block in > GNU Radio Companion without the need for a “gain_impl.h” and > “gain_impl.cc” under your lib directory.  I know those are generated > usually be RFNOCMODTOOL (screenshot below from UHD3), do we not need > to create those for UHD4? > https://kb.ettus.com/Getting_Started_with_RFNoC_Development > > Thank you! > > -Dexter >