Gadgets are configured by editing the gadget: line in /boot/usbninja/options.txt. Currently, multiple gadget support is still in testing (see FAQ number 6.), but it seems to work very well. You can specify multiple gadgets by separating them with commas.
E.g. gadget: serial, storage, ethernet_ecm
The /boot directory is accessible from parition one of the MicroSD which is formatted as FAT32. This makes it easy to configure the USB Ninja from MacOS and Windows (as well as Linux) who don't have good ext4 support as standard.
NOTE: Any option can be omitted by this file and the defaults will automatically be chosen. If you wanted, you could just have gadget: <YOUR_GADGET> and nothing else.
To use the USB-To-Serial gadget, set gadget to serial in options.txt. A TTY will be made available via /dev/ttyGS0 on the USB Ninja which shows up as /dev/ttyACM0 on the (Linux) host. If using Windows, you can use PuTTY. Either way, ensure that the baud rate is set to 115200. See SERIAL.md for more information.
To use the USB-To-Ethernet gadget, you can use either ethernet_ecm or ethernet_rndis. (Simply using ethernet will default to ethernet_ecm). To make a long story short, use ethernet_rndis for Windows and ethernet_ecm for everything else. See ETHERNET.md for more information.
To parse the /boot/usbninja/hid.txt and send the keystrokes contained within it as HID packets, use the hid_payload gadget. The format of hid.txt is very simple and straightforward - see HID.md for more information.
The mass storage gadget is activated by including storage on the gadget: line in options.txt. It makes the image in /lib/usbninja/storage.img available as a mass storage device to the host. For details on how to change the default image (only 1GB) and more, see STORAGE.md.