Datasheet

282
ATmega16U4/32U4 [DATASHEET]
Atmel-7766J-USB-ATmega16U4/32U4-Datasheet_04/2016
• Bit 7 - Reserved
The value read from this bits is always 0. Do not set this bit.
• Bit 6 - UPRSMI - Upstream Resume Interrupt Flag
Set by hardware when the USB controller is sending a resume signal called “Upstream Resume”. This triggers
an USB interrupt if UPRSME is set.
Shall be cleared by software (USB clocks must be enabled before). Setting by software has no effect.
• Bit 5 - EORSMI - End Of Resume Interrupt Flag
Set by hardware when the USB controller detects a good “End Of Resume” signal initiated by the host. This
triggers an USB interrupt if EORSME is set.
Shall be cleared by software. Setting by software has no effect.
• Bit 4 - WAKEUPI - Wake-up CPU Interrupt Flag
Set by hardware when the USB controller is re-activated by a filtered non-idle signal from the lines (not by an
upstream resume). This triggers an interrupt if WAKEUPE is set.
Shall be cleared by software (USB clock inputs must be enabled before). Setting by software has no effect.
See “Suspend, Wake-up and Resume” on page 272 for more details.
• Bit 3 - EORSTI - End Of Reset Interrupt Flag
Set by hardware when an “End Of Reset” has been detected by the USB controller. This triggers an USB
interrupt if EORSTE is set.
Shall be cleared by software. Setting by software has no effect.
• Bit 2 - SOFI - Start Of Frame Interrupt Flag
Set by hardware when an USB “Start Of Frame” PID (SOF) has been detected (every 1ms). This triggers an
USB interrupt if SOFE is set.
• Bit 1 - Reserved
The value read from this bits is always 0. Do not set this bit
• Bit 0 - SUSPI - Suspend Interrupt Flag
Shall be cleared by software. Setting by software has no effect. The interrupt bits are set even if their
corresponding ‘Enable’ bits is not set.
See “Suspend, Wake-up and Resume” on page 272 for more details.
See for more details.
Bit 76543210
-
UPRSMI EORSMI WAKEUPI EORSTI SOFI - SUSPI UDINT
Read/Write
Initial Value 0 0 0 0 0 0 0 0