Flake lock file updates:

• Updated input 'nixpkgs':
    'path:/nix/store/0ljv28gdwhlfm9629qaxg95g04jzcf9j-source?lastModified=1670009809&narHash=sha256-yt/dQ32Vz4WenDLu4XeHbnXFxiHbTcnU0WwiLW5Ce6c%3D&rev=660e7737851506374da39c0fa550c202c824a17c' (2022-12-02)
  → 'path:/nix/store/z0513hax0dsbix0x89wr7fca8sa99sxc-source?lastModified=1702233072&narHash=sha256-H5G2wgbim2Ku6G6w%2BNSaQaauv6B6DlPhY9fMvArKqRo%3D&rev=781e2a9797ecf0f146e81425c822dca69fe4a348' (2023-12-10)

It doesn't work, yet, because the VS Code plugin demands a newer
version.

We needed a simple PWM controller at Camp and this board was available...

We need one more level of indirection.

The record number of Modbus is not enough to address 2 MB of flash
memory so we add an additional offset.