{
  description = "Wearables";

  inputs = {
    nixpkgs.url = "nixpkgs/nixos-21.11";
  };

  outputs = { self, nixpkgs }:
    let 
      version = builtins.string 0 8 self.lastModifiedDate;
      supportedSystems = [ "x86_64-linux" "avr-none" ];
    in
    {
      defaultPackage."x86_64-linux" =
        let
          pkgs = import nixpkgs { system = "x86_64-linux"; };
          avr = pkgs.pkgsCross.avr.buildPackages;
        in pkgs.stdenv.mkDerivation rec {
          name = "hello";
          src = ./.;

          MCU = "attiny85";
          CHIP_SELECT = "AVR_ATtiny85";
          F_CPU = "8000000";
          CFLAGS = ''-O -finline-functions -funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums -Wall -Wstrict-prototypes -DF_CPU=${F_CPU} -std=gnu99 -D__${CHIP_SELECT}__=1 -mmcu=${MCU}'';

          buildPhase = ''
            set -x

            ${avr.gcc}/bin/avr-gcc ${CFLAGS} -I${src}/base -o base.o -c ${src}/base/base.c
            ${avr.gcc}/bin/avr-gcc ${CFLAGS} -I${src}/base -o sk9822.o -c ${src}/sk9822/sk9822.c
            ${avr.gcc}/bin/avr-gcc ${CFLAGS} -I${src}/base -I${src}/sk9822 -o main.o -c ${src}/flame/main.c
            ${avr.gcc}/bin/avr-gcc ${CFLAGS} -o main.elf main.o sk9822.o base.o
            $OBJCOPY -O ihex main.elf main.hex
            '';
          installPhase = ''
            mkdir $out
            cp main.elf main.hex $out
            '';
        };

      devShell."x86_64-linux" =
        let
          pkgs = import nixpkgs { system = "x86_64-linux"; };
          avr = with pkgs.pkgsCross.avr.buildPackages; [
            binutils
            gcc
            gdb
            avrdude
            simavr
            gtkwave
          ];
        in
        pkgs.mkShell {
          name = "Wearables-shell";
          buildInputs = avr;

          GCC = pkgs.pkgsCross.avr.buildPackages.gcc;
          SIMAVR = pkgs.pkgsCross.avr.buildPackages.simavr;
        };
    };
}