USB Device Controller
1591
SPNU503C – March 2018
Copyright © 2018, Texas Instruments Incorporated
Universal Serial Bus (USB)
29.3.1.23 Transmit Endpoint n Configuration Register (EPn_TX)
This read/write register gives the device configuration for non-control transmit endpoint n (1:15). The
endpoints size fields must match the values sent by the USB device controller to the USB host in
response to the GET_CONFIGURATION_DESCRIPTOR during configuration phase.
NOTE:
The USB device controller must fill this field before setting SYSCON1.CFG_LOCK and must
not change the values once SYSCON1.CFG_LOCK is set.
Figure 29-50. Transmit Endpoint n Configuration Register (EPn_TX)
[address = FCF78A62h to FCF78A7Eh]
15
14
13
12
11
10
8
EPn_TX_
VALID
EPn_TX_SIZE_
DB
EPn_TX_SIZE
EPn_TX_ISO
EPn_TX_PTR
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
7
0
EPn_TX_PTR
R/W-0
LEGEND: R/W = Read/Write; -
n
= value at reset
Table 29-54. Transmit Endpoint n Configuration Register (EPn_TX) Field Descriptions
Bit
Field
Value
Description
15
EPn_TX_VALID
The transmit endpoint n valid bit must be set by the USB device controller to allow transmit
endpoint n to be used for USB transfers as part of the device configuration. If not set, all
transactions to this endpoint are ignored by the core.
0
Transmit endpoint n does not exist for this configuration.
1
Transmit endpoint n is part of the device configuration.
Values after USB device controller hardware reset are low, after USB reset is unchanged.
14
EPn_TX_SIZE_DB
Transmit non-ISO (or ISO) endpoint n double buffer. This bit is only for non-ISO endpoints
used in DMA mode. For ISO endpoints, which are always double buffered, this bit is
endpoint size MSB. For non-ISO endpoints that are not used in a DMA transfer, double
buffering is not provided.
This bit must be set by the USB device controller to allow double buffering for transmit non-
ISO endpoint n, when used in a DMA transfer. This is used to reduce the number of
transactions resulting in NAK handshake.
0
No double buffer for non-ISO transmit endpoint n.
1
Double buffer used for non-ISO transmit endpoint n.
Values after system reset or USB reset is unchanged. Or transmit ISO endpoint n size[2]