atmega32u4-16mu ATMEL Corporation, atmega32u4-16mu Datasheet - Page 295

• Manufacturer Part Number: atmega32u4-16mu
• Description: Atmega32u4 8-bit Avr Microcontroller With 32k Bytes Of Isp Flash And Usb Controller
• Manufacturer: ATMEL Corporation

23.15.2
23.16 Overflow
23.17 Interrupts
7766A–AVR–03/08
CRC Error
A CRC error can occur during OUT stage if the USB controller detects a bad received packet. In
this situation, the STALLEDI interrupt is triggered. This does not prevent the RXOUTI interrupt
from being triggered.
In Control, Isochronous, Bulk or Interrupt Endpoint, an overflow can occur during OUT stage, if
the host attempts to write in a bank that is too small for the packet. In this situation, the OVERFI
interrupt is triggered (if enabled). The packet is acknowledged and the RXOUTI interrupt is also
triggered (if enabled). The bank is filled with the first bytes of the packet.
It is not possible to have overflow error during IN stage, in the CPU side, since the CPU should
write only if the bank is ready to access data (TXINI=1 or RWAL=1).
The next figure shows all the interrupts sources:
Figure 23-4. USB Device Controller Interrupt System
There are 2 kind of interrupts: processing (i.e. their generation are part of the normal processing)
and exception (errors).
Processing interrupts are generated when:
Exception Interrupts are generated when:
• VBUS plug-in detection (insert, remove)( VBUSTI )
• Upstream resume( UPRSMI )
• End of resume( EORSMI )
• Wake up( WAKEUPI )
• End of reset (Speed Initialization)( EORSTI )
• Start of frame( SOFI , if FNCERR=0)
• Suspend detected after 3 ms of inactivity( SUSPI )
• CRC error in frame number of SOF( SOFI , FNCERR=1)
EORSMI
UPRSMI
UDINT.6
UDINT.5
WAKEUPI
UDINT.4
EORSTI
UDINT.3
UDINT.2
UDINT.0
SUSPI
SOFI
UPRSME
EORSME
UDIEN.6
UDIEN.5
WAKEUPE
UDIEN.4
EORSTE
UDIEN.3
UDIEN.2
UDIEN.0
SUSPE
SOFE
USB Device
Interrupt
ATmega32U4
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