Wipe SD Card - portapack-mayhem/mayhem-firmware GitHub Wiki
Fast fill 512 random block into your sdcard to destroy all data that it has. Do not use this tool unless you are sure you currently need to destroy all the data and you wanted it not recoverable [1].
Warning: This tool is not for formatting or cleaning sdcard. As long as you wiped your SD Card with this tool, you would need to format it again with a computer or other similar devices (But not your hackrf or portapack) before you can use it again (save things into it).
p.s. [1] ^ This is not a guarantee.