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UM10316_0
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 00.06 — 17 December 2008
152 of 571
1.
How to read this chapter
The USB device controller is used in parts LPC2921/23/25, LPC2927/29, LPC2930, and
LPC2939.
2.
Introduction
The Universal Serial Bus (USB) is a four-wire bus that supports communication between a
host and one or more (up to 127) peripherals. The host controller allocates the USB
bandwidth to attached devices through a token-based protocol. The bus supports hot
plugging and dynamic configuration of the devices. All transactions are initiated by the
host controller.
The host schedules transactions in 1 ms frames. Each frame contains a Start-Of-Frame
(SOF) marker and transactions that transfer data to or from device endpoints. Each device
can have a maximum of 16 logical or 32 physical endpoints. There are four types of
transfers defined for the endpoints. Control transfers are used to configure the device.
Interrupt transfers are used for periodic data transfer. Bulk transfers are used when the
rate of transfer is not critical. Isochronous transfers have guaranteed delivery time but no
error correction.
For more information on the Universal Serial Bus, see the USB Implementers Forum
website.
The USB device controller on the LPC29xx enables full-speed (12 Mb/s) data exchange
with a USB host controller.
UM10316
Chapter 13: LPC29xx USB device
Rev. 00.06 — 17 December 2008
User manual
Table 113. USB related acronyms, abbreviations, and definitions used in this chapter
Acronym/abbreviation Description
AHB
Advanced High-performance bus
ATLE
Auto Transfer Length Extraction
ATX
Analog Transceiver
DD
DMA Descriptor
DDP
DMA Description Pointer
DMA
Direct Memory Access
EOP
End-Of-Packet
EP
Endpoint
EP_RAM
Endpoint RAM
FS
Full Speed
LED
Light Emitting Diode
LS
Low Speed
MPS
Maximum Packet Size
NAK
Negative Acknowledge
PLL
Phase Locked Loop