AT90USB646_0607 Datasheet, PDF (297/435 Pages) ATMEL Corporation – 8-bit Microcontroller with 64/128K Bytes of ISP Flash and USB Controller

AT90USB64/128
23.12 Control Pipe management
A Control transaction is composed of 3 phases:
• SETUP
• Data (IN or OUT)
• Status (OUT or IN)
The firmware has to change the Token for each phase.
The initial data toggle is set for the corresponding token (ONLY for Control Pipe):
• SETUP: Data0
• OUT: Data1
• IN: Data1 (expected data toggle)
23.13 OUT Pipe management
The Pipe must be configured and not frozen first.
Note: if the firmware decides to switch to suspend mode (clear SOFEN) even if a bank is ready
to be sent, the USB controller will automatically exit from Suspend mode and the bank will be
sent.
The TXOUT bit is set by hardware when the current bank becomes free. This triggers an inter-
rupt if the TXOUTE bit is set. The FIFOCON bit is set at the same time. The CPU writes into the
FIFO and clears the FIFOCON bit to allow the USB controller to send the data.
7593D–AVR–07/06
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