UM10208_2
© NXP B.V. 2007. All rights reserved.
User manual
Rev. 02 — 1 June 2007
224 of 362
NXP Semiconductors
UM10208
Chapter 17: LPC2800 USB Device
8.18 USB Endpoint Max Packet Size Register (USBMaxSize - 0x8004 1004)
This register does not apply to Control Endpoint 0, which has a fixed Max Packet Size of
64 bytes, and a Setup buffer that contains 8 bytes. When this register is written, the
endpoint’s Data Count Register is re-initialized to the new value.
Table 248. USB Endpoint Max Packet Size Register (USBMaxSize - 0x8004 1004)
Bit
Symbol
Description
Master
Reset
value
Bus
Reset
value
10:0
FIFOSize Writing this field sets the FIFO size (in bytes) for the endpoint
selected by the USBEIX register. The value written to this
frame should be the same as the value indicated to the host
during the enumeration process. Because the maximum packet
size is a function of the type of endpoint and the mode (HS/FS),
this register will typically need to be re-programmed when a
shift between HS and FS mode occurs.
0
0
12:11 NTRANS This field applies only in HS mode. It controls the number of
transactions allowed per microframe:
00: 1 packet allowed per microframe
01: 2 packets allowed per microframe
10: 3 packets allowed per microframe
11: reserved, do not write this value
0
0
31:13 -
Reserved, software should not write ones to reserved bits. The
values read from reserved bits is not defined.
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