LM3S3749 Datasheet, PDF (706/898 Pages) Texas Instruments – Stellaris® LM3S3749 Microcontroller

Universal Serial Bus (USB) Controller
Register 74: USB Host Transmit Interval Endpoint 1 (USBTXINTERVAL1),
offset 0x11B
Register 75: USB Host Transmit Interval Endpoint 2 (USBTXINTERVAL2),
offset 0x12B
Register 76: USB Host Transmit Interval Endpoint 3 (USBTXINTERVAL3),
offset 0x13B
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, as follows:
Transfer Type
Interrupt
Isochronous
Bulk
Speed
Low-Speed or Full-Speed
Full-Speed
Full-Speed
Valid values (m)
0x01 – 0xFF
0x01 – 0x10
0x02 – 0x10
Interpretation
The polling interval is m frames.
The polling interval is 2^(m-1) frames.
The NAK Limit is 2^(m-1) frames. A value of 0
or 1 disables the NAK timeout function.
USB Host Transmit Interval Endpoint 1 (USBTXINTERVAL1)
Base 0x4005.0000
Offset 0x11B
Type R/W, reset 0x00
7
6
5
4
3
2
1
0
TXPOLL / NAKLMT
Type R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit/Field
7:0
Name
TXPOLL / NAKLMT
Type
R/W
Reset
0x00
Description
TX Polling / NAK Limit
The polling interval for interrupt/isochronous transfers; the NAK limit for
bulk transfers. See table above for valid entries; other values are
reserved.
706
November 17, 2011
Texas Instruments-Production Data