SAM4L Datasheet, PDF (391/1185 Pages) ATMEL Corporation – ATSAM ARM-based Flash MCU

ATSAM4L4/L2
For IN endpoints, this indicates the number of banks filled by the user and ready for IN transfers. When all banks are free an
EPnINT interrupt will be triggered if NBUSYBKE is one.
For OUT endpoints, this indicates the number of banks filled by OUT transactions from the host. When all banks are busy an
EPnINT interrupt will be triggered if NBUSYBKE is one.
• RAMACERI: Ram Access Error Interrupt
This bit is cleared when the RAMACERIC bit is written to one, acknowledging the interrupt.
This bit is set when a RAM access underflow error occurs during an IN data stage.
• DTSEQ: Data Toggle Sequence
This field is set to indicate the PID of the current bank:
DTSEQ
0
0
0
1
1
X
Data Toggle Sequence
Data0
Data1
Reserved
For IN transfers, this indicates the data toggle sequence that will be used for the next packet to be sent.
For OUT transfers, this value indicates the data toggle sequence of the data received in the current bank.
• STALLEDI: STALLed Interrupt
This bit is cleared when the STALLEDIC bit is written to one, acknowledging the interrupt.
This bit is set when a STALL handshake has been sent and triggers an EPnINT interrupt if STALLEDE is one.
• CRCERRI: CRC Error Interrupt
This bit is cleared when the CRCERRIC bit is written to one, acknowledging the interrupt.
This bit is set when a CRC error has been detected in an isochronous OUT endpoint bank, and triggers an EPnINT interrupt if
CRCERRE is one.
• NAKINI: NAKed IN Interrupt
This bit is cleared when the NAKINIC bit is written to one, acknowledging the interrupt.
This bit is set when a NAK handshake has been sent in response to an IN request from the host, and triggers an EPnINT
interrupt if NAKINE is one.
• NAKOUTI: NAKed OUT Interrupt
This bit is cleared when the NAKOUTIC bit is written to one, acknowledging the interrupt.
This bit is set when a NAK handshake has been sent in response to an OUT request from the host, and triggers an EPnINT
interrupt if NAKOUTE is one.
• ERRORFI: Isochronous Error flow Interrupt
This bit is cleared when the ERRORFIC bit is written to one, acknowledging the interrupt.
This bit is set, for isochronous IN/OUT endpoints, when an errorflow (underflow or overflow) error occurs, and triggers an
EPnINT interrupt if ERRORFE is one.
An underflow can occur during IN stage if the host attempts to read from an empty bank. A zero-length packet is then
automatically sent by the USBC.
An overflow can also occur during OUT stage if the host sends a packet while the bank is already full, resulting in the packet
being lost. This is typically due to a CPU not being fast enough.
This bit is inactive (cleared) for bulk and interrupt IN/OUT endpoints and it means RXSTPI for control endpoints.
• RXSTPI: Received SETUP Interrupt
This bit is cleared when the RXSTPIC bit is written to one, acknowledging the interrupt and freeing the bank.
This bit is set, for control endpoints, to signal that the current bank contains a new valid SETUP packet, and triggers an EPnINT
interrupt if RXSTPE is one.
This bit is inactive (cleared) for bulk and interrupt IN/OUT endpoints and it means UNDERFI for isochronous IN/OUT endpoints.
• RXOUTI: Received OUT Data Interrupt
This bit is cleared when the RXOUTIC bit is written to one, acknowledging the interrupt. For control endpoints, it releases the
bank. For other endpoint types, the user should clear the FIFOCON bit to free the bank. RXOUTI shall always be cleared before
clearing FIFOCON to avoid missing an interrupt.
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