USB in an embedded system without RTOS

Question

I have no experience of embedded USB stacks so my question is, can I run it without an OS?

Of course it must be possible to run without OS, but will things be MUCH easier if I have one?

I want to use it to save data to a attached USB Mass Storage Device.

Answer 1

If your USB device is on-chip, your chip vendor will almost certainly have example code for USB that may include mass storage. You won't need an OS, but interrupt handling will be necessary and a file system too.

Your USB controller will need host or OTG capability - if it is only device capable, then you cannot connect to another USB device, only a host.

The benefit of an OS - or at least a simple RTOS kernel - is that you can schedule file system activity concurrently with other processing tasks. The OS in that case would not necessarily make things easier, but it may make your system more responsive to critical tasks and events.

Answer 2

I have used usb stacks in the past with PIC18F2550 (8 bits) and LPC1343 (32 bits ARM-Cortex M3) microcontrollers without any problems.