Getting Started with RFNoC Development
Contents
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Overview
This application note gives a brief introduction into the steps required to start developing RFNoC blocks on your computer. First, you need to make sure that you have all the tools required to do RFNoC development. Then, we will set up a development sandbox in which you can do your RFNoC development. Finally, we will run through the basic steps required to actually write custom RFNoC blocks.
Prerequisites
For any of this to work, you need to make sure you have all the tools to do both software and FPGA development. Confirm you have the following tools installed:
- Xilinx Vivado. The specific version depends on the branch and state of the FPGA code and is very important. Make sure to install the correct version.
- Software build tools. If you can compile UHD from source, you have all the necessary components (If you're using PyBOMBS
Please make sure these tools are available before proceeding to the next step.
Creating a development environment
In the following, we will assume that GNU Radio is used as a helper tool for RFNoC development. Note that GNU Radio is by no means required to use or develop RFNoC, but it makes it a great deal easier. So in order to get your development environment set up, you will need the following software packages:
- UHD - GNU Radio - gr-ettus
The cleanest way to set this up is to install everything into a dedicated directory. PyBOMBS is the simplest way to do this. If you haven't already downloaded and installed PyBOMBS, you can do so by running the following commands:
$ sudo pip install git+https://github.com/gnuradio/pybombs.git $ pybombs recipes add gr-recipes git+https://github.com/gnuradio/gr-recipes.git $ pybombs recipes add ettus git+https://github.com/EttusResearch/ettus-pybombs.git
From here, the easiest way to set up a PyBOMBS development environment is to run the following command:
$ pybombs prefix init ~/prefix/rfnoc -R rfnoc [-a alias]
This will do the following:
- Create a directory in ~/prefix/rfnoc - Clone UHD, FPGA, GNU Radio, and gr-ettus sources into that directory - Compile and install all the software
Then, enable the prefix:
$ cd ~/prefix/rfnoc $ source ./setup_env.sh
PyBOMBS is by no means required to do any of these steps. If you wish to install the software manually, follow the individual install notes for GNU Radio, UHD and gr-ettus and make sure they are reachable by linkers and compilers.
To manually download the software, use these git clone commands, which will select the correct branches:
$ git clone --recursive -b rfnoc-radio-redo https://github.com/EttusResearch/uhd.git $ git clone -b maint https://github.com/gnuradio/gnuradio.git # master branch is also fine $ git clone -b radio-redo https://github.com/EttusResearch/gr-ettus.git
If you have already UHD, GNU Radio and/or gr-ettus installed, it would be sufficient to checkout to the branches mentioned and pull them. Thereafter, build each of the repositories (first UHD, then GNU Radio, then gr-ettus).
RFNoC Framework
rfnocmodtool
In order to minimize the effort needed to implement a new RFNoC module, this gr_modtool-based tool provides the basic structure of the necessary files needed for the user to start with the development of his/her custom design right away. As it is gr_modtool-based, the manual found at [1] is also a great reference for this tool. Here, we discuss the features specific for the RFNoC modtool.
With the use of RFNoC ModTool, you can skip the struggle of locating the files of your design at different locations that depend (until now) on the location of your UHD and gr-ettus installation paths. Instead, you focus on your implementation and the tool takes care of boilerplate code and linking.
Tool Installation
The tool is currently shipped within gr-ettus (radio-redo branch), so by installing gr-ettus, rfnocmodtool automatically becomes available.
Tool Utilization
After the installation, you are ready to use the tool to generate standard code for your Out-of-tree module. To check the usage of the tool, just type:
$ rfnocmodtool help linux; GNU C++ version 4.8.4; Boost_105400; UHD_003.010.rfnoc-radio-redo-0-fd4d734e Usage: rfnocmodtool <command> [options] -- Run <command> with the given options. rfnocmodtool help -- Show a list of commands. rfnocmodtool help <command> -- Shows the help for a given command. List of possible commands: Name Aliases Description ===================================================================== disable dis Disable block (comments out CMake entries for files) info getinfo,inf Return information about a given module remove rm,del Remove block (delete files and remove Makefile entries) makexml mx Make XML file for GRC block bindings add insert Add block to the out-of-tree module. newmod nm,create Create a new out-of-tree module rename mv Rename a block in the out-of-tree module.
If you have used the gr_modtool provided by GNURadio, you'll be familiar with this usage.
Creating an RFNoC OOT Module
At this point you are all set up to start generating your own RFNoC OOT and if you were thinking that it is just as easy as it is with gr_modtool, you are completely right! Simply go to your prefixes source location (~/prefix/rfnoc/src) and type:
$ rfnocmodtool newmod [NAME OF THE MODULE]
In the following, assume we want to create a module with the name 'example'. You can write the name of your module right after the 'newmod' command, but if you happen to forget it, the tool will ask for it interactively. This will create a folder containing the basic folders that you may need for a functional module.
$ rfnocmodtool newmod example linux; GNU C++ version 4.8.4; Boost_105400; UHD_003.010.rfnoc-radio-redo-0-fd4d734e Creating out-of-tree module in ./rfnoc-example... Done. Use 'rfnocmodtool add' to add a new block to this currently empty module. $ ls rfnoc-example/ $ apps cmake CMakeLists.txt docs examples grc include lib MANIFEST.md python README.md rfnoc swig
In contrast with gr_modtool, this includes a folder called 'rfnoc', which is where we put the UHD/FPGA files (more details below).
Adding custom blocks
Now you can start adding blocks to your module. The only thing to do is go inside of the module you just created and type:
$ rfnocmodule add [NAME OF THE BLOCK]
For demonstrative purposes, lets create a block named 'copy'. As for the new module, the tool will ask you for the name of the block if you not put it in the first line. There is a bunch of directives that you could pass to the tool, but if you run it without any of these directives you should expect the following interactive parsing output:
$ rfnocmodtool add copy linux; GNU C++ version 4.8.4; Boost_105400; UHD_003.010.rfnoc-radio-redo-0-fd4d734e RFNoC module name identified: example Block/code identifier: copy Enter valid argument list, including default arguments: Add Python QA code? [Y/n] Add C++ QA code? [y/N] Block NoC ID (Hexadecimal): 2626 Skip Block Controllers Generation? [y/N] Skip Block interface Generation? [y/N]
The tool is going to ask you about a valid argument list, in case you have that clear at this stage of your design, and for the generation of QA codes which are, such as in the case of gr_modtool, optional. Right after that, specific RFNoC questions appear:
- NoC ID: This ID is a Hexadecimal number which serves as identification between the hardware part and the software part of the design. It can be as long as 16 0-9 A-F digits. If you dont provide the NoC ID, it will be set to a random number.
- Block Controllers Generation: The block controllers are the C++ control that you can apply to the UHD-part of the design. In this files, you can add more control over this layer of your design. However, if you can manage to add the control you need over NoC-Script, you can omit the cpp/hpp block control files generation, reason why this is optional.
- Block Interface: Analogously to the block controllers, you may want to add more design specific functionality to your design at the GNURadio interface. To do that, you add the logic into the block-interface files. In the same manner, if your control can be managed by adding NoC-Script to your xml file, you can disregard the generation of files.
Also, it is important to notice that if you don't intend to use the block controllers or you are not sure if you would, the presence
Adding file 'lib/copy_impl.h'... Adding file 'lib/copy_impl.cc'... Adding file 'include/example/copy.h'... Adding file 'include/example/copy_block_ctrl.hpp'... Adding file 'lib/copy_block_ctrl_impl.cpp'... Editing swig/example_swig.i... Adding file 'python/qa_copy.py'... Editing python/CMakeLists.txt... Adding file 'grc/example_copy.xml'... Adding file 'rfnoc/blocks/copy.xml'... Adding file 'rfnoc/fpga-src/noc_block_copy.v'...
Other Resources
[1] GNURadio OutOfTree Modules: http://gnuradio.org/redmine/projects/gnuradio/wiki/OutOfTreeModules
https://github.com/EttusResearch/uhd/wiki/RFNoC:-Getting-Started
https://github.com/EttusResearch/uhd/wiki/RFNoC:--Specification
