USB Registers
1737
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
Universal Serial Bus (USB) Controller
27.5.34 USBCSRL0 Register (Offset = 0x102) [reset = 0x0]
USB Control and Status Endpoint 0 Low (USBCSRL0)
OTG A / Host
OTG B / Device
USBCSRL0 is an 8-bit register that provides control and status bits for endpoint 0.
USBCSRL0 for OTG A / Host is shown in
and described in
USBCSRL0 for OTG B / Device is shown in
and described in
Return to
Figure 27-39. USBCSRL0 Register (OTG A / Host)
7
6
5
4
3
2
1
0
NAKTO
STATUS
REQPKT
ERROR
SETUP
STALLED
TXRDY
RXRDY
R/W-0x0
R/W-0x0
R/W-0x0
R/W-0x0
R/W-0x0
R/W-0x0
R/W-0x0
R/W-0x0
Table 27-44. USBCSRL0 Register Field Descriptions (OTG A / Host)
Bit
Field
Type
Reset
Description
7
NAKTO
R/W
0x0
NAK Time-out.
Software must clear this bit to allow the endpoint to continue.
0x0 = No time-out.
0x1 = Indicates that endpoint 0 is halted following the receipt of NAK
responses for longer than the time set by the USBNAKLMT register.
6
STATUS
R/W
0x0
STATUS Packet.
Setting this bit ensures that the DT bit is set in the USBCSRH0
register so that a DATA1 packet is used for the STATUS stage
transaction.
This bit is automatically cleared when the STATUS stage is over.
0x0 = No transaction.
0x1 = Initiates a STATUS stage transaction. This bit must be set at
the same time as the TXRDY or REQPKT bit is set.
5
REQPKT
R/W
0x0
Request Packet.
This bit is cleared when the RXRDY bit is set.
0x0 = No request.
0x1 = Requests an IN transaction.
4
ERROR
R/W
0x0
Error.
Software must clear this bit.
0x0 = No error.
0x1 = Three attempts have been made to perform a transaction with
no response from the peripheral. The EP0 bit in the USBTXIS
register is also set in this situation.
3
SETUP
R/W
0x0
Setup Packet.
Setting this bit always clears the DT bit in the USBCSRH0 register to
send a DATA0 packet.
0x0 = Sends an OUT token.
0x1 = Sends a SETUP token instead of an OUT token for the
transaction. This bit should be set at the same time as the TXRDY
bit is set.
2
STALLED
R/W
0x0
Endpoint Stalled.
Software must clear this bit.
0x0 = No handshake has been received.
0x1 = A STALL handshake has been received.