I have a low power consumption circuit using the AT90USB647 that acts as a Host controller and read/writes data with USB flash memory sticks.
Currently the whole circuit, without USB Host enabled, consumpts 75uA (average). The controller wakes up each 32ms from Power Down using the WDT interrupt, then do some works and finally get into sleep (Power Down) again.
The phillosophy of the USB Host subcircuit is taken from the AT90USB647 datasheet (revision K, 11/09), page 250, Figure 21-8. The UID pin is used as a general purpose I/O. The datasheet can be found here:
Everything about the Host controller, FAT32 and comunication with the USB flash memory stick is ready and functions just fine.
What I want to do is to use a method of waking up the controller from power down mode, whenever a USB flash memory stick is connected, keeping this way the current consumption as low as possible (near 75uA).
At the same datasheet page 53, Table 7-2, it says that the controller wakes up from sleep from one of these reasons: VBUSTI, WAKEUPI, IDTI, HWUPI.
If you have the experiense on this, could you please suggest me the right method or even an example of setting it?