A BASH script used to set the USB OTG gadget mode on a Raspberry Pi.
The USB port on a Raspberry Pi normally operates in host mode and accepts devices such as a USB keyboard, USB flash drive, USB ethernet, etc. However, it is possible to have the Raspberry Pi act as a USB device in place of a host.
The Raspberry Pi can act as a USB ethernet device, USB serial port, etc.
Use sudo to run the BASH script from the command line...
sudo ./otg-set-mode.sh [mode]
The default mode is g_ether if no mode parameter is provided.
Other possible modes include:
- Serial (g_serial)
- Ethernet (g_ether)
- Mass storage (g_mass_storage)
- MIDI (g_midi)
- Audio (g_audio)
- Keyboard/Mouse (g_hid)
- Mass storage and Serial (g_acm_ms)
- Ethernet and Serial (g_cdc)
- Multi (g_multi) - Allows you to configure 2 from Ethernet, Mass storage and Serial
- Webcam (g_webcam)
- Printer (g_printer)
- Gadget tester (g_zero)
After running the script the changes will take effecgt after the next reboot.
The script will modify two files on the boot partition to enable the selected OTG mode.
A kernel modules-load parameter is added to /boot/cmdline.txt to load the dwc2 module when the kernel loads. I.E.
modules-load=dwc2,g_ether
And a dtoverlay setting is added to /boot/config.txt to configure the device tree for OTG mode when the Raspberry Pi boots. I.E.
dtoverlay=dwc2
Additional setup may be needed to take advantage of the new OTG device settings. I.E.
When using the g_serial mode it may be desirable to attach a console to the new USB serial device. The following command will enable the serial console...
sudo systemctl enable getty@ttyGS0.service
If the mode is set to g_ether then it may be desirable to configure an IP address on the USB ethernet device and install a DHCP server so the Raspberry Pi can provide an IP address to any system that connects to the USB port.