The primary firmware source code for USB HackRF devices is hackrf_usb. Most of the other directories contain firmware source code for test and development. The common directory contains source code shared by multiple HackRF firmware projects. The cpld directory contains HDL source for the CPLD. The firmware is set up for compilation with the GCC toolchain available here: https://code.launchpad.net/gcc-arm-embedded Required dependency: https://github.com/mossmann/libopencm3 If you are using git, the preferred way to install libopencm3 is to use the submodule: $ cd .. $ git submodule init $ git submodule update $ cd firmware/libopencm3 $ make To build and install a standard firmware image for HackRF One: $ cd hackrf_usb $ mkdir build $ cd build $ cmake .. -DBOARD=RAD1O $ make $ hackrf_spiflash -w hackrf_usb.bin For loading firmware into RAM with DFU you will also need: http://dfu-util.gnumonks.org/ To start up HackRF One in DFU mode, hold down the DFU button while powering it on or while pressing and releasing the RESET button. Release the DFU button after the 3V3 LED illuminates. With dfu-util and dfu-suffix (from the dfu-util package) installed and with the HackRF operating in DFU mode, you can build firmware for RAM and load it with: $ cd hackrf_usb $ mkdir build $ cd build $ cmake .. -DRUN_FROM=RAM $ make hackrf_usb-program Alternatively you can load a .dfu file from a release package with: $ dfu-util --device 1fc9:000c --alt 0 --download hackrf_usb_ram.dfu