1012
11100B–ATARM–31-Jul-12
SAM4S Series [Preliminary]
• TXPKTRDY: Transmit Packet Ready
This flag is cleared by the USB device.
This flag is set by the USB device firmware.
Read:
0 = There is no data to send.
1 = The data is waiting to be sent upon reception of token IN.
Write:
0 = Can be used in the procedure to cancel transmission data. (See,
Section 38.6.2.5 “Transmit Data Cancellation” on
1 = A new data payload has been written in the FIFO by the firmware and is ready to be sent.
This flag is used to generate a Data IN transaction (device to host). Device firmware checks that it can write a data payload
in the FIFO, checking that TXPKTRDY is cleared. Transfer to the FIFO is done by writing in the UDP_FDRx register. Once
the data payload has been transferred to the FIFO, the firmware notifies the USB device setting TXPKTRDY to one. USB
bus transactions
can start. TXCOMP is set once the data payload has been received by the host.
After setting or clearing this bit, a wait time of 3 UDPCK clock cycles and 3 peripheral clock cycles is required before
accessing DPR.
• FORCESTALL: Force Stall (used by Control, Bulk and Isochronous Endpoints)
Read:
0 = Normal state.
1 = Stall state.
Write:
0 = Return to normal state.
1 = Send STALL to the host.
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.
Control endpoints: During the data stage and status stage, this bit indicates that the microcontroller cannot complete the
request.
Bulk and interrupt endpoints: This bit notifies the host that the endpoint is halted.
The host acknowledges the STALL, device firmware is notified by the STALLSENT flag.
• RX_DATA_BK1: Receive Data Bank 1 (only used by endpoints with ping-pong attributes)
This flag generates an interrupt while it is set to one.
Write (Cleared by the firmware):
0 = Notifies USB device that data have been read in the FIFO’s Bank 1.
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 1.
1 = A data packet has been received, it has been stored in FIFO's Bank 1.
Summary of Contents for SAM4S Series
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