Aegis

Aegis is a fully open-source FPGA, from the silicon up.

Existing open-source FPGA efforts either reverse-engineer proprietary architectures (Project IceStorm, Apicula) or build tooling around closed silicon (Yosys, nextpnr). The silicon itself has always been proprietary. Aegis starts at the other end: the fabric design is open, the toolchain is open, and the path to real silicon goes through open PDKs and shuttle services like wafer.space.

The project generates parameterized FPGA devices with LUT4, BRAM, DSP, SerDes, and clock management tiles, along with everything needed to synthesize user designs onto them and tape out the fabric itself to a foundry.

Devices

Aegis Terra 1

The first Aegis device, targeting GF180MCU via wafer.space.

Resource	Count
LUT4	~2880
BRAM (128x8)	128 tiles
DSP18 (18x18 MAC)	64 tiles
I/O pads	224
SerDes	4
Clock tiles	2 (8 outputs)
Routing tracks	4 per edge

nix build .#terra-1          # Generate IP (SV, JSON, chipdb, techmap)
nix build .#terra-1-tapeout  # Full RTL-to-GDS for fab submission

Toolchain

Each device gets a complete FPGA toolchain via the tools output:

# Synthesize a Verilog design to Aegis cells
yosys -c synth.tcl  # using $tools/share/yosys/aegis/*_cells.v + *_techmap.v

# Place and route on the fabric
nextpnr-aegis-terra_1 --json design_mapped.json --write design_pnr.json

# Pack into a bitstream
terra_1-pack --pnr design_pnr.json --output design.bin

# Simulate with the bitstream loaded
terra_1-sim --bitstream design.bin --cycles 1000 --vcd waves.vcd

ASIC Tapeout

The tapeout pipeline synthesizes the FPGA fabric itself to PDK standard cells:

nix build .#terra-1-tapeout
ls result/
# terra_1_synth.v      — gate-level netlist (Yosys)
# terra_1_final.def    — placed & routed layout (OpenROAD)
# terra_1.gds          — GDS2 for fab submission
# terra_1_layout.png   — layout render
# timing.rpt           — timing analysis
# power.rpt            — power report

Supports GF180MCU (wafer.space) and Sky130 PDKs.

Building

Requires Nix with flakes enabled.

# Build the default package (aegis-ip-tools)
nix build

# Build Terra 1 IP
nix build .#terra-1

# Run the blinky example as a check
nix build .#checks.$(nix eval --raw nixpkgs#system).terra-1-blinky

# Enter development shell
nix develop

Architecture

The FPGA fabric is generated by ROHD (a Dart HDL framework) and outputs synthesizable SystemVerilog. The architecture follows Xilinx-style conventions:

• CLB: LUT4 + D flip-flop + MUXCY carry chain (18-bit config)
• Tile: CLB + 4-directional routing muxes (46-bit config)
• BRAM: Dual-port 128x8 block RAM (8-bit config)
• DSP: 18x18 multiply-accumulate with optional pipeline (16-bit config)
• IO: Bidirectional pad with input/output registers (8-bit config)
• SerDes: Protocol-agnostic serializer/deserializer (32-bit config)
• Clock: 4-output clock divider with phase control (49-bit config)

Configuration is loaded via a serial shift register chain: clock tiles -> IO tiles -> SerDes tiles -> fabric tiles (row-major).