
USB Registers
1760
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
Universal Serial Bus (USB) Controller
27.5.47 USBTXINTERVALn Register [reset = 0x0]
USB Host Transmit Interval Endpoint 1 (USBTXINTERVAL1), offset 0x11B
USB Host Transmit Interval Endpoint 2 (USBTXINTERVAL2), offset 0x12B
USB Host Transmit Interval Endpoint 3 (USBTXINTERVAL3), offset 0x13B
USB Host Transmit Interval Endpoint 4 (USBTXINTERVAL4), offset 0x14B
USB Host Transmit Interval Endpoint 5 (USBTXINTERVAL5), offset 0x15B
USB Host Transmit Interval Endpoint 6 (USBTXINTERVAL6), offset 0x16B
USB Host Transmit Interval Endpoint 7 (USBTXINTERVAL7), offset 0x17B
OTG A / Host
USBTXINTERVALn is an 8-bit register that, for interrupt and isochronous transfers, defines the polling
interval for the currently selected transmit endpoint. For bulk endpoints, this register defines the number of
frames after which the endpoint should time out on receiving a stream of NAK responses.
The USBTXINTERVALn register value defines a number of frames:
Table 27-63. USBTXINTERVALn Register Values
Transfer Type
Speed
Valid values (m)
Interpretation
Interrupt
Low Speed or
Full Speed
0x01 to 0xFF
The polling interval is m frames.
Interrupt
High Speed
0x01 to 0x10
Polling interval is 2
(m-1)
microframes.
Isochronous
Full Speed or
High Speed
0x01 to 0x10
The polling interval is 2
(m-1)
frames/microframes.
Bulk
Full-Speed or
High Speed
0x02 to 0x10
The NAK Limit is 2
(m-1)
frames/microframes. A value of 0 or 1
disables the NAK time-out function.
USBTXINTERVALn is shown in
and described in
Return to
Figure 27-58. USBTXINTERVALn Register
7
6
5
4
3
2
1
0
TXPOLL/NAKLMT
R/W-0x0
Table 27-64. USBTXINTERVALn Register Field Descriptions
Bit
Field
Type
Reset
Description
7-0
TXPOLL/NAKLMT
R/W
0x0
TX Polling / NAK Limit.
The polling interval for interrupt/isochronous transfers or the NAK
limit for bulk transfers.
See
for valid entries; other values are reserved.