USB Device Controller
1592
SPNU503C – March 2018
Copyright © 2018, Texas Instruments Incorporated
Universal Serial Bus (USB)
Table 29-54. Transmit Endpoint n Configuration Register (EPn_TX) Field Descriptions (continued)
Bit
Field
Value
Description
13-12
EPn_TX_SIZE
The transmit endpoint n size field contains the endpoint n FIFO size value. Status flags
(FIFO_EMPTY, FIFO_FULL) and underrun condition are based on this value for all IN
transactions to endpoint n.
Non-ISO (bits 13-12):
0
8 bytes
1h
16 bytes
2h
32 bytes
3h
64 bytes
ISO (bits 14-12):
0
8 bytes
1h
16 bytes
2h
32 bytes
3h
64 bytes
4h
128 bytes
5h
256 bytes
6h
512 bytes
7h
1023 bytes
Note: For ISO endpoints, a size of 1023 bytes takes up the whole memory and prevents
programming with a 2K-byte USB device controller.
Values after USB device controller hardware reset or USB reset are unchanged (which
means that values are unknown until first write access).
11
EPn_TX_ISO
The transmit ISO endpoint n field must be set if the transmit endpoint n type is isochronous
in the desired device configuration. If not set, the endpoint type is bulk or interrupt (the
hardware does not distinguish bulk type from interrupt).
0
Transmit endpoint n type is bulk or interrupt.
1
Transmit endpoint n type is isochronous.
Value after USB reset is unchanged.
10-0
EPn_TX_PTR
The transmit endpoint n pointer field contains the address of the transmit endpoint n pointer.
For ISO endpoints or for non-ISO endpoints that allow double-buffering, (2 × TX buffer size)
must be reserved for ping-pong.
0
Address = BASE
1h
Address = BASE + 8 bytes
2h
Address = BASE + 16 bytes
3h
Address = BASE + 24 bytes
:
:
FFh
Address = BASE + 2040 bytes
Values after USB device controller hardware reset or USB reset are unchanged (which
means that values are unknown until first write access).
Pointer value must be set to a value < FFh, because the memory size is 2K bytes and a
pointer coded value = FFh corresponds to 2040 bytes. Addressing upper bytes results in
memory overlap.