Datasheet

282
7766E–AVR–04/10
ATmega16U4/ATmega32U4
Then, clear by software to complete the reset operation and start using the endpoint.
• 7-6 - Reserved
The value read from these bits is always 0. Do not set these bits.
• 5 - STALLRQ - STALL Request Handshake Bit
Set to request a STALL answer to the host for the next handshake.
Cleared by hardware when a new SETUP is received. Clearing by software has no effect.
See Section 22.11, page 270 for more details.
• 4 - STALLRQC - STALL Request Clear Handshake Bit
Set to disable the STALL handshake mechanism.
Cleared by hardware immediately after the set. Clearing by software has no effect.
See Section 22.11, page 270 for more details.
3
• RSTDT - Reset Data Toggle Bit
Set to automatically clear the data toggle sequence:
For OUT endpoint: the next received packet will have the data toggle 0.
For IN endpoint: the next packet to be sent will have the data toggle 0.
Cleared by hardware instantaneously. The firmware does not have to wait that the bit is cleared.
Clearing by software has no effect.
• 2 - Reserved
The value read from these bits is always 0. Do not set these bits.
• 1 - Reserved
The value read from these bits is always 0. Do not set these bits.
• 0 - EPEN - Endpoint Enable Bit
Set to enable the endpoint according to the device configuration. Endpoint 0 shall always be
enabled after a hardware or USB reset and participate in the device configuration.
Clear this bit to disable the endpoint. See Section 22.6, page 267 for more details.
• 7-6 - EPTYPE1:0 - Endpoint Type Bits
Set this bit according to the endpoint configuration:
Bit 76543210
- - STALLRQ STALLRQC RSTDT - - EPEN UECONX
Read/Write R R W W W R R R/W
Initial Value 0 0 0 0 0 0 0 0
Bit 76543210
EPTYPE1:0 - - - - - EPDIR UECFG0X
Read/WriteR/WR/WRRRRRR/W
Initial Value 0 0 0 0 0 0 0 0