We are currently prototyping a project that periodically spins up a USB drive to store data. We took advantage of the example msd fatfs project.
Because this is a low power application, the program loop is roughly:
1. Run at a lower speed recording data and sleeping as much as possible
2. When a buffer fills, change clock speeds and components to support a USB MSD device
3. Call USB Host Init
4. Call USB Tasks in a loop until the device attaches.
5. Write Data
6. Detach the disk
7. USB Host Deinit
This above program loop works great...for the first 8 attachments. After that, the USB Tasks ALWAYS fail with an enumeration failed error.
What is the proper way to detach and deinitialize ? One things I had to do in order to get it to work more than once was to manually set the .occupied field to 0. Because of the 8 successes, I'm guessing something is getting used and not correctly freed. However, I have been unsuccessful in all my attempts to get it to "correctly" detach or remove the device.
The example program only initializes and then runs in a loop, so I haven't been able to find any examples that show bringing down the USB stack and bringing it back up.
Thanks in advance,
Chandler
