Registers
1727
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Universal Serial Bus 2.0 (USB) Controller
34.4.44 NAKLimit0 Register (Host mode only) (HOST_NAKLIMIT0)
The NAKlimit0 register (Host mode only) (HOST_NAKLIMIT0) is shown in
and described in
.
Figure 34-70. NAKLimit0 Register (Host mode only) (HOST_NAKLIMIT0)
7
5
4
0
Reserved
EP0NAKLIMIT
R-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 34-74. NAKLimit0 Register (Host mode only) (HOST_NAKLIMIT0) Field Descriptions
Bit
Field
Value
Description
7-5
Reserved
0
Reserved
4-0
EP0NAKLIMIT
0-1Fh
Sets the number of frames/microframes (high-speed transfers) after which Endpoint 0 should time
out on receiving a stream of NAK responses. The number of frames/microframes selected is 2
(-1)
(where m is the value set in the register, valid values 2-16). If the host receives NAK responses
from the target for more frames than the number represented by the Limit set in this register, the
endpoint will be halted.
Note: A value of 0 or 1 disables the NAK timeout function.
34.4.45 Transmit Interval Register (Host mode only) (HOST_TXINTERVAL)
The transmit interval register (Host mode only) (HOST_TXINTERVAL) is shown in
and
described in
Figure 34-71. Transmit Interval Register (Host mode only) (HOST_TXINTERVAL)
7
0
POLINTVL_NAKLIMIT
R/W-0
LEGEND: R/W = Read/Write; -
n
= value after reset
Table 34-75. Transmit Interval Register (Host mode only) (HOST_TXINTERVAL) Field Descriptions
Bit
Field
Value
Description
7-0
POLINTVL_NAKLIMIT
0-FFh
For Interrupt and Isochronous transfers, defines the polling interval for the currently-selected
transmit endpoint. For Bulk endpoints, sets the number of frames/microframes after which
the endpoint should timeout on receiving a stream of NAK responses. There is a transmit
interval register for each configured transmit endpoint (except Endpoint 0). In each case, the
value that is set defines a number of frames/microframes (High-Speed transfers), as
follows:
Transfer Type
Speed
Valid values (m)
Interpretation
Interrupt
Low Speed or
Full Speed
1-255
Polling interval is m frames
High Speed
1-16
Polling interval is 2
(-1)
microframes
Isochronous
Full Speed or
High Speed
1-16
Polling interval is 2
(-1)
frames/microframes
Bulk
Full Speed or
High Speed
2-16
NAK Limit is 2
(-1)
frames/microframes
Note: A value of 0 or 1 disables the NAK timeout function.