USB Device Controller
1589
SPNU503C – March 2018
Copyright © 2018, Texas Instruments Incorporated
Universal Serial Bus (USB)
29.3.1.22 Receive Endpoint n Configuration Register (EPn_RX)
This read/write register gives the device configuration for non-control receive endpoint n (1:15). The
endpoints size fields must match values sent by the USB device controller to the USB host in response to
the GET_CONFIGURATION_DESCRIPTOR during configuration phase.
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.
Values depend on whether the reset action comes from USB device controller (CPU) or USB host.
Figure 29-49. Receive Endpoint n Configuration Register (EPn_RX)
[address = FCF78A42h to FCF78A5Eh]
15
14
13
12
11
10
8
EPn_RX_
VALID
EPn_RX_SIZE_
DB
EPn_RX_SIZE
EPn_RX_ISO
EPn_RX_PTR
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
7
0
EPn_RX_PTR
R/W-0
LEGEND: R/W = Read/Write; -
n
= value at reset
Table 29-53. Receive Endpoint n Configuration Register (EPn_RX) Field Descriptions
Bit
Field
Value
Description
15
EPn_RX_VALID
The receive endpoint n valid bit must be set by the USB device controller to allow receive
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
Receive endpoint n does not exist for this configuration.
1
Receive endpoint n is part of the device configuration.
Values after USB device controller hardware reset are low, after USB reset is unchanged.
14
EPn_RX_SIZE_DB
Receive non-ISO (or ISO) endpoint n double-buffer (DB). This bit is only for non-ISO
endpoints. For ISO endpoints, which are always double-buffered, this bit is endpoint size
MSB. This bit must be set by the USB device controller to allow double buffering for receive
non-ISO endpoint n. This is used to reduce number of transactions resulting in NAK
handshake.
0
No double buffer for non-ISO receive endpoint n.
1
Double buffer used for non-ISO receive endpoint n.
Values after USB device controller hardware reset or USB reset are unchanged (which
means that values are unknown until first write access).