File Types
ArduPilot Pre-Built Binaries https://firmware.ardupilot.org
*.apjfiles: these are “ArduPilot JSON” firmwares, which contain a firmware that can be loaded by ArduPilot compatible ground station software*.px4files: these are an older name for an apj file, and use the same format*.hexfiles: these are firmwares in Intel hex format, for loading with DFU loading tools. These are used for boards which don’t come with an ArduPilot compatible bootloader*_with_bl.hexfiles: these are variants of the hex files with the bootloader built-in. They can be used to install both the bootloader and ArduPilot vehicle firmware in one step using a DFU loading tool