iCE40 Bitstream Size Reduction - Bitstreams and Reconfiguration Time Measurements

The HDF5 file contains data from an experiment concerning bitstream size reduction for Lattice iCE40 FPGAs.

Five projects were synthesized with two different toolchains and afterwards compacted and compressed. Two compaction levels were applied to each of the ten original bistreams, resulting in a total of 30 bitstreams. The ten original bitstreams were also compressed with two different compression tools, resulting in 20 compressed versions.

The reconfiguration time for each of the 30 bitstreams was measured 10.000 times.

Toolchains:

• Lattice iCEcube2
• Open-source toolchain (Yosys, nextpnr, Project IceStorm)

Projects:

• blinky: A simple example design that is included in the open-source toolchain.
• ehw: An evolved design.
• attosoc: A minimal RISC-V system on a chip, that is used for tests in the open-source toolchain.
• updater: A design that receives a new configuration, decrypts it (AES) and writes it to flash.
• picosoc: RISC-V system on a chip

Compaction levels:

• original: Uncompacted bitstream
• builtin: Compacted with two methods also available in iCEcube2
• compact: Compacted with all five methods

Compression tools:

• icecompr: Included in Project IceStorm
• gzip: Version 1.9, compression level --best

File structure:

The data is organzied hierarchical. It is first split between bitstreams, measurements and compressed versions.  Bitstreams and measurements then are divided by toolchain, then by project and finally by compaction level. The compressed versions are divided by toolchain, then by project and finally by compression tool.