at91sam9g20-cu ATMEL Corporation, at91sam9g20-cu Datasheet - Page 682

• Manufacturer Part Number: at91sam9g20-cu
• Description: At91 Arm Thumb Microcontrollers
• Manufacturer: ATMEL Corporation

682
AT91SAM9G20 Preliminary
When a setup transaction is received after a stall handshake, STALLSENT must be cleared in
order to prevent interrupts due to STALLSENT being set.
Figure 37-12. Stall Handshake (Data IN Transfer)
Figure 37-13. Stall Handshake (Data OUT Transfer)
3. The microcontroller is notified that the device has sent the stall by polling the
USB Bus
Packets
FORCESTALL
STALLSENT
USB Bus
Packets
FORCESTALL
STALLSENT
STALLSENT to be set. An endpoint interrupt is pending while STALLSENT is set. The
microcontroller must clear STALLSENT to clear the interrupt.
Data OUT PID
Data IN
PID
Set by USB Device
Data OUT
Stall PID
Set by Firmware
Stall PID
Set by Firmware
Interrupt Pending
Interrupt Pending
Set by
USB Device
Cleared by Firmware
Cleared by Firmware
Cleared by Firmware
6384B–ATARM–15-Dec-08