I want to connect my Pi (or any other inexpensive device, really) to my TV via USB. This connection should have the TV as a master and the Pi as a slave.
Network is not an option, as the TV supports neither Samba nor any other way of writing over Ethernet.
The use of this build is to save recordings the TV makes onto a storage server, so I don't need to buy an external drive and also have the recordings in a central place.
Is this possible and how?
First the device's USB controller needs to support this in hardware. Only some, but not all, Raspberry Pi models support it, as do a few other single-board computers. Search for "OTG mode" or "dwc2" together with your board's model.
(As a general rule, full-size type-A ports will never be able to act as a device.)
Once you have enabled the necessary hardware (e.g. loaded drivers for the dwc2 controller), you can then load one of the "gadget" drivers in Linux. There is g_mass_storage for emulating a USB storage device, g_serial for emulating a USB-to-serial converter, g_ether for emulating a USB-Ethernet adapter, and quite a few others.
Further resources:
