Datasheet

SAM9G20
DS60001516A-page 684  2017 Microchip Technology Inc.
RX_DATA_BK0: Receive Data Bank 0
This flag generates an interrupt while it is set to one.
Write (Cleared by the firmware):
0: Notify USB peripheral device that data have been read in the FIFO's Bank 0.
1: To leave the read value unchanged.
Read (Set by the USB peripheral):
0: No data packet has been received in the FIFO's Bank 0.
1: A data packet has been received, it has been stored in the FIFO's Bank 0.
When the device firmware has polled this bit or has been interrupted by this signal, it must transfer data from the FIFO to the microcontroller
memory. The number of bytes received is available in RXBYTCENT field. Bank 0 FIFO values are read through the UDP_FDRx register.
Once a transfer is done, the device firmware must release Bank 0 to the USB peripheral device by clearing RX_DATA_BK0.
After setting or clearing this bit, a wait time of 3 UDPCK clock cycles and 3 peripheral clock cycles is required before accessing DPR.
RXSETUP: Received Setup
This flag generates an interrupt while it is set to one.
Read:
0: No setup packet available.
1: A setup data packet has been sent by the host and is available in the FIFO.
Write:
0: Device firmware notifies the USB peripheral device that it has read the setup data in the FIFO.
1: No effect.
This flag is used to notify the USB device firmware that a valid Setup data packet has been sent by the host and successfully received by
the USB device. The USB device firmware may transfer Setup data from the FIFO by reading the UDP_FDRx register to the microcon-
troller memory. Once a transfer has been done, RXSETUP must be cleared by the device firmware.
Ensuing Data OUT transaction is not accepted while RXSETUP is set.
STALLSENT: Stall Sent (Control, Bulk Interrupt Endpoints)/ISOERROR (Isochronous Endpoints)
This flag generates an interrupt while it is set to one.
STALLSENT: This ends a STALL handshake.
Read:
0: The host has not acknowledged a STALL.
1: Host has acknowledged the stall.
Write:
0: Resets the STALLSENT flag, clears the interrupt.
1: No effect.
This is mandatory for the device firmware to clear this flag. Otherwise the interrupt remains.
Refer to chapters 8.4.5 and 9.4.5 of the Universal Serial Bus Specification, Rev. 2.0 for more information on the STALL handshake.
ISOERROR: A CRC error has been detected in an isochronous transfer.
Read:
0: No error in the previous isochronous transfer.
1: CRC error has been detected, data available in the FIFO are corrupted.
Write:
0: Resets the ISOERROR flag, clears the interrupt.
1: No effect.