Nxp Semiconductors UM10237 User Manual

UM10237_2

© NXP B.V. 2008. All rights reserved.

 

The USB controller is configured using the following registers:

1. Power: In the PCONP register (

), set bit PCUSB.

Remark: On reset, the USB block is disabled (PCUSB = 0).

2. Clock: see 

.

3. Pins: Select USB pins and their modes in PINSEL0 to PINSEL5 and PINMODE0 to 

PINMODE5 (

4. Wakeup: Use the INTWAKE register (

) to enable activity on the USB bus 

port to wake up the microcontroller from Power-down mode. 

5. Interrupts: See 

. Interrupts are enabled in the VIC using the 

VICIntEnable register (

).

6. Initialization: see 

.

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 LPC2400 enables full-speed (12 Mb/s) data exchange 
with a USB host controller.

 

AHB

Advanced High-performance bus

ATLE

Auto Transfer Length Extraction

ATX

Analog Transceiver

DD

DMA Descriptor

DDP

DMA Description Pointer 

DMA

Direct Memory Access