USB Registers
1753
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
Universal Serial Bus (USB) Controller
Table 27-57. USBRXCSRLn Register Field Descriptions (OTG A / Host) (continued)
Bit
Field
Type
Reset
Description
3
DATAERR/NAKTO
R/W
0x0
Data Error / NAK Time-out.
0x0 = Normal operation.
0x1 = Isochronous endpoints only:
Indicates that RXRDY is set and the data packet has a CRC or bit-
stuff error. This bit is cleared when RXRDY is cleared.
Bulk endpoints only:
Indicates that the receive endpoint is halted following the receipt of
NAK responses for longer than the time set by the NAKLMT field in
the USBRXINTERVALn register.
Software must clear this bit to allow the endpoint to continue.
2
ERROR
R/W
0x0
Error.
Software must clear this bit.
This bit is only valid when the receive endpoint is operating in Bulk
or Interrupt mode.
In Isochronous mode, it always returns zero.
0x0 = No error.
0x1 = Three attempts have been made to receive a packet and no
data packet has been received. The EPn bit in the USBRXIS register
is set in this situation.
1
FULL
R
0x0
FIFO Full.
0x0 = The receive FIFO is not full.
0x1 = No more packets can be loaded into the receive FIFO.
0
RXRDY
R/W
0x0
Receive Packet Ready.
If the AUTOCLR bit in the USBRXCSRHn register is set, then the
this bit is automatically cleared when a packet of USBRXMAXPn
bytes has been unloaded from the receive FIFO.
If the AUTOCLR bit is clear, or if packets of less than the maximum
packet size are unloaded, then software must clear this bit manually
when the packet has been unloaded from the receive FIFO.
0x0 = No data packet has been received.
0x1 = A data packet has been received. The EPn bit in the
USBRXIS register is also set in this situation.
Figure 27-53. USBRXCSRLn Register (OTG B / Device)
7
6
5
4
3
2
1
0
CLRDT
STALLED
STALL
FLUSH
DATAERR
OVER
FULL
RXRDY
W1C-0x0
R/W-0x0
R/W-0x0
R/W-0x0
R-0x0
R/W-0x0
R-0x0
R/W-0x0
Table 27-58. USBRXCSRLn Register Field Descriptions (OTG B / Device)
Bit
Field
Type
Reset
Description
7
CLRDT
W1C
0x0
Clear Data Toggle.
Writing a 1 to this bit clears the DT bit in the USBRXCSRHn register.
6
STALLED
R/W
0x0
Endpoint Stalled.
Software must clear this bit.
0x0 = A STALL handshake has not been transmitted.
0x1 = A STALL handshake has been transmitted.
5
STALL
R/W
0x0
Send STALL.
Software must clear this bit to terminate the STALL condition.
This bit has no effect where the endpoint is being used for
isochronous transfers.
0x0 = No effect.
0x1 = Issues a STALL handshake.