USB Registers
1745
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
Universal Serial Bus (USB) Controller
27.5.39 USBTXMAXPn Register [reset = 0x0]
USB Maximum Transmit Data Endpoint 1 (USBTXMAXP1), offset 0x110
USB Maximum Transmit Data Endpoint 2 (USBTXMAXP2), offset 0x120
USB Maximum Transmit Data Endpoint 3 (USBTXMAXP3), offset 0x130
USB Maximum Transmit Data Endpoint 4 (USBTXMAXP4), offset 0x140
USB Maximum Transmit Data Endpoint 5 (USBTXMAXP5), offset 0x150
USB Maximum Transmit Data Endpoint 6 (USBTXMAXP6), offset 0x160
USB Maximum Transmit Data Endpoint 7 (USBTXMAXP7), offset 0x170
OTG A / Host
OTG B / Device
The USBTXMAXPn 16-bit register defines the maximum amount of data that can be transferred through
the transmit endpoint in a single operation.
Bits 10:0 define (in bytes) the maximum payload transmitted in a single transaction. The value set can be
up to 1024 bytes but is subject to the constraints placed by the USB Specification on packet sizes for bulk,
interrupt and isochronous transfers in full-speed operation.
The total amount of data represented by the value written to this register must not exceed the FIFO size
for the transmit endpoint, and must not exceed half the FIFO size if double-buffering is required.
If this register is changed after packets have been sent from the endpoint, the transmit endpoint FIFO
must be completely flushed (using the FLUSH bit in USBTXCSRLn) after writing the new value to this
register.
NOTE:
USBTXMAXPn must be set to an even number of bytes for proper interrupt generation in
USB DMA Basic Mode.
USBTXMAXPn is shown in
and described in
Return to
Figure 27-46. USBTXMAXPn Register
15
14
13
12
11
10
9
8
RESERVED
MAXLOAD
R-0x0
R/W-0x0
7
6
5
4
3
2
1
0
MAXLOAD
R/W-0x0
Table 27-51. USBTXMAXPn Register Field Descriptions
Bit
Field
Type
Reset
Description
15-11
RESERVED
R
0x0
10-0
MAXLOAD
R/W
0x0
Maximum Payload.
This field specifies the maximum payload in bytes per transaction.