OUTPUT_FILENAME

This variable is optional. You can use it to provide the name of the output file. This also denotes the type of file, based on file extension. For example:

OUTPUT_FILENAME = output.hex

will generate an Intel HEX file. This definition can also hold a list of output files, for example:

OUTPUT_FILENAME = output.elf output.hex output.bin

will generate both ELF, Intel HEX and binary files.