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Manta: An In-Situ Debugging Tool for Programmable Hardware
Manta is a tool for debugging FPGA designs over an interface like UART or Ethernet. It has two modes for doing this, downlink and uplink. The downlink mode feels similar to a logic analyzer, in that Manta provides a waveform view of a configurable set of signals, which get captured when some trigger condition is met. The uplink mode allows a host machine to remotely set values of registers on the FPGA via a python interface. This permits rapid prototyping of logic in Python, and a means of incrementally migrating it to HDL. A more detailed description of each mode is below.
Manta is written in Python, and generates SystemVerilog HDL. It's cross-platform, and its only dependencies are pySerial and pyYAML. The SystemVerilog templates are included in the Python source, so only a single python file must be included in your project.
Downlink
Manta's downlink mode works by taking a JSON file describing the ILA configuration, and autogenerating a debug core with SystemVerilog. This gets included in the rest of the project's HDL, and is synthesized and flashed on the FPGA. It can then be controlled by a host machine connected over a serial port. The host can arm the core, and then when a trigger condition is met, the debug output is wired back to the host, where it's saved as a waveform file. This can then be opened and inspected in a waveform viewer like GTKWave.
This is similar to Xilinx's Integrated Logic Analyzer (ILA) and Intel/Altera's SignalTap utility.
Uplink:
Getting Started
Since Manta is designed to be both cross-platform and unintrusive to your project source, it's packaged as a single python file with the HDL templates built in. This isn't the cleanest thing to develop with, so it's developed as a set of files that are stitched together into a single Python script. This isn't compilation since we're not going to machine code - we're just building a script, not a binary.
Using a prebuilt script
Copy manta.py into the root of your project directory. You'll also need a configuration file - check out examples/ if you need some help putting one of those together.
Building from source
Clone the repo, and then run build.py. This will output an executable manta with no file extension, which you're free to use.
Examples
Examples can be found under examples/.
About
Manta was originally developed as part of my Master's Thesis at MIT in 2023, done under the supervision of Joe Steinmeyer. But I think it's a neat tool, so I'm still working on it :)