Warning: The script-based build system will not be maintained in versions newer than 1.4. Please consider using CMake instead.

Firstly, you will need to copy all files from old-build-system directory to the project root. Then you will be able to run ./genconf.sh script to generate build configuration (details on usage are in its help message: ./genconf.sh --help). The available options more or less correspond to the ones described in Building liblightmodbus.

After the configuration is generated, you can use make command to trigger the build. In order to build for AVR, use dedicated makeifile - make -f makefile-avr.