Register Descriptions
1333
SPRUH22I – April 2012 – Revised November 2019
Copyright © 2012–2019, Texas Instruments Incorporated
M3 Universal Serial Bus (USB) Controller
18.5.28 USB Maximum Transmit Data Endpoint n Registers (USBTXMAXP[1]-USBTXMAXP[15])
The USB maximum transmit data endpoint
n
16-bit registers (USBTXMAXP[
n
]) define the maximum
amount of data that can be transferred through the selected 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:
USBTXMAXP[
n
] must be set to an even number of bytes for proper interrupt generation in
μ
DMA
Basic Mode.
For the specific offset for each register see
.
Mode(s):
OTG A or Host
OTG B or Device
The USBTXMAXP[
n
] registers are shown in
and described in
.
Figure 18-33. USB Maximum Transmit Data Endpoint n Registers (USBTXMAXP[n])
15
11
10
0
Reserved
MAXLOAD
R-0
R/W-000
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 18-36. USB Maximum Transmit Data Endpoint n Registers(USBTXMAXP[n])
Field Descriptions
Bit
Field
Value
Description
15-11
Reserved
0
Reserved
10-0
MAXLOAD
Maximum Payload specifies the maximum payload in bytes per transaction.