My MCU is a AT91SAM7se256.

In my application, the MCU is backed by battery, so it is always on regardless of USB connection status. The problem however is that I cannot get the USB peripheral to clear the addressed bit in the UDP_GLB_STAT register, so when I attach the USB cable to a Linux box, the host fails a number of times before a successful attachment can be made.

Any suggestions on how to make a "hot" USB attach look the same to the host as a "cold" USB attach with a system that has been through reset?

Hi,
we use an Arm9, but maybe our approach work on your device also:
The USB driver (taken from the ATMEL software package for our controller) has the functions USBD_Disconnect and USBD_Connect and we do a "softreset" of USB by just calling these 2 functions. It then behaves like unplugging and replugging the usb cable.

Thanks for replying,

we use the same trick with disconnecting/reconnecting (aside from some added deep power save-stuff) to simulate a fresh connection.