10.1. General Setup and Usage

10.1.1. Sources

All FPGA prototyping-related collateral and sources are located in the fpga top-level Chipyard directory. This includes the fpga-shells submodule and the src directory that hold both Scala, TCL and other collateral.

10.1.2. Generating a Bitstream

Generating a bitstream for any FPGA target using Vivado is similar to building RTL for a software RTL simulation. Similar to a software RTL simulation (Simulating A Custom Project), you can run the following command in the fpga directory to build a bitstream using Vivado:


# or

make SUB_PROJECT=<sub_project> bitstream

The SUB_PROJECT make variable is a way to meta make variable that sets all of the other make variables to a specific default. For example:

make SUB_PROJECT=vcu118 bitstream

# converts to

make SBT_PROJECT=fpga_platforms MODEL=VCU118FPGATestHarness VLOG_MODEL=VCU118FPGATestHarness MODEL_PACKAGE=chipyard.fpga.vcu118 CONFIG=RocketVCU118Config CONFIG_PACKAGE=chipyard.fpga.vcu118 GENERATOR_PACKAGE=chipyard TB=none TOP=ChipTop BOARD=vcu118 FPGA_BRAND=... bitstream

Some SUB_PROJECT defaults are already defined for use, including vcu118 and arty. These default SUB_PROJECT’s setup the necessary test harnesses, packages, and more for the Chipyard make system. Like a software RTL simulation make invocation, all of the make variables can be overridden with user specific values (ex. include the SUB_PROJECT with a CONFIG and CONFIG_PACKAGE override). In most cases, you will just need to run a command with a SUB_PROJECT and an overridden CONFIG to point to. For example, building the BOOM configuration on the VCU118:

make SUB_PROJECT=vcu118 CONFIG=BoomVCU118Config bitstream

That command will build the RTL and generate a bitstream using Vivado. The generated bitstream will be located in your designs specific build folder (generated-src/<LONG_NAME>/obj). However, like a software RTL simulation, you can also run the intermediate make steps to just generate Verilog or FIRRTL.

10.1.3. Debugging with ILAs on Supported FPGAs

ILA (integrated logic analyzers) can be added to certain designs for debugging relevant signals. First, open up the post synthesis checkpoint located in the build directory for your design in Vivado (it should be labeled post_synth.dcp). Then using Vivado, add ILAs (and other debugging tools) for your design (search online for more information on how to add an ILA). This can be done by modifying the post synthesis checkpoint, saving it, and running make ... debug-bitstream. This will create a new bitstream called top.bit in a folder named generated-src/<LONG_NAME>/debug_obj/. For example, running the bitstream build for an added ILA for a BOOM config.:

make SUB_PROJECT=vcu118 CONFIG=BoomVCU118Config debug-bitstream


For more extensive debugging tools for FPGA simulations including printf synthesis, assert synthesis, instruction traces, ILAs, out-of-band profiling, co-simulation, and more, please refer to the FireSim platform.