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UM10316_0
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 00.06 — 17 December 2008
173 of 571
NXP Semiconductors
UM10316
Chapter 13: LPC29xx USB device
length 130 bytes, then the software sends two 64-byte packets and the remaining 2 bytes
in the last packet. So, a total of 3 packets are sent on USB. USBTxPLen is a write only
register.
9.5.5 USB Control register (USBCtrl - 0xE010 C228)
This register controls the data transfer operation of the USB device. It selects the endpoint
buffer that is accessed by the USBRxData and USBTxData registers, and enables
reading and writing them. USBCtrl is a read/write register.
9.6 SIE command code registers
The SIE command code registers are used for communicating with the Serial Interface
Engine. See
Section 13–11 “Serial interface engine command description”
for more
information.
Table 147. USB Transmit Packet Length register (USBTxPLen - address 0xE010 C224) bit
description
Bit
Symbol
Value Description
Reset
value
9:0
PKT_LNGTH
-
The remaining number of bytes to be written to the
selected endpoint buffer. This field is decremented by 4 by
hardware after each write to USBTxData. When this field
decrements to 0, the TxENDPKT bit will be set in
USBDevIntSt.
0x000
31:10 -
-
Reserved, user software should not write ones to reserved
bits. The value read from a reserved bit is not defined.
NA
Table 148. USB Control register (USBCtrl - address 0xE010 C228) bit description
Bit
Symbol
Value
Description
Reset
value
0
RD_EN
Read mode control. Enables reading data from the OUT
endpoint buffer for the endpoint specified in the
LOG_ENDPOINT field using the USBRxData register.
This bit is cleared by hardware when the last word of
the current packet is read from USBRxData.
0
0
Read mode is disabled.
1
Read mode is enabled.
1
WR_EN
Write mode control. Enables writing data to the IN
endpoint buffer for the endpoint specified in the
LOG_ENDPOINT field using the USBTxData register.
This bit is cleared by hardware when the number of
bytes in USBTxLen have been sent.
0
0
Write mode is disabled.
1
Write mode is enabled.
5:2
LOG_ENDPOINT -
Logical Endpoint number.
0x0
31:6 -
-
Reserved, user software should not write ones to
reserved bits. The value read from a reserved bit is not
defined.
NA