Wake-Up Function - Fujitsu F2MC-16LX Hardware Manual

16-bit microcontroller mb90330 series

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Wake-up Function

To shift a USB device from suspend status to wake-up status, the USB protocol

provides the following two ways:

Remote wake-up from device

Wake-up from host PC

The above is explained.

Remote Wake-up

A device must perform processing in the following steps:

1. Recover the device from stop mode through external interrupt.

2. RESUM of the UDCC register is set.

3. RESUM of the UDCC register is cleared.

Wake-up from Host

For the devices, the following processing is required:

1. Set oscillation stabilizing time to be not more than 10 ms.

2. Enter an interrupt due to the WKUP factor and clear WKUP of UDCS that is the interrupt cause and

return from the interrupt.

Figure 13.4-7 Remote Wake-up Operation

Suspend state

stabilization time

Extrnal interrupt

Figure 13.4-8 Wake-up Operation from Host

Suspend state

Soft set, clear

not less than 20ms

stabilization time

CHAPTER 13 USB FUNCTION