NXP LPC2468 USB接口解方案

NXP公司的LPC2468微控制器采用16位/32位ARM7TDMI-S CPU内核,具有实时调试接口. LPC2468集成了高速512KB片内闪存, 10/100以太网媒体接入控制器(MAC),带4KB端点RAM的USB全速器件/主/OTG控制器,四个UART,两个CAN通路和一些串行通信接口. LPC2468非常适合多用途的通信应用.本文介绍了LPC2468的主要特性,功能方框图以及五种USB接口解决方案.

NXP Semiconductors designed the LPC2468 microcontroller around a 16-bit/32-bit

ARM7TDMI-S CPU core with real-time debug interfaces that include both JTAG and

embedded trace. The LPC2468 has 512 kB of on-chip high-speed flash memory. This

flash memory includes a special 128-bit wide memory interface and accelerator

architecture that enables the CPU to execute sequential instructions from flash memory at

the maximum 72 MHz system clock rate. This feature is available only on the LPC2000

ARM microcontroller family of products. The LPC2468 can execute both 32-bit ARM and

16-bit Thumb instructions. Support for the two instruction sets means engineers can

choose to optimize their application for either performance or code size at the sub-routine

level. When the core executes instructions in Thumb state it can reduce code size by more than 30 % with only a small loss in performance while executing instructions in ARM state maximizes core performance.

The LPC2468 microcontroller is ideal for multipurpose communication applications. It

incorporates a 10/100 Ethernet Media Access Controller (MAC), a USB full-speed

Device/Host/OTG Controller with 4 kB of endpoint RAM, four UARTs, two Controller Area

Network (CAN) channels, an SPI interface, two Synchronous Serial Ports (SSP), three I2C interfaces, and an I2S interface. Supporting this collection of serial communications

interfaces are the following feature components; an on-chip 4 MHz internal precision

oscillator, 98 kB of total RAM consisting of 64 kB of local SRAM, 16 kB SRAM for

Ethernet, 16 kB SRAM for general purpose DMA, 2 kB of battery powered SRAM, and an

External Memory Controller (EMC). These features make this device optimally suited for

communication gateways and protocol converters. Complementing the many serial

communication controllers, versatile clocking capabilities, and memory features are

various 32-bit timers, an improved 10-bit ADC, 10-bit DAC, two PWM units, four external

interrupt pins, and up to 160 fast GPIO lines. The LPC2468 connects 64 of the GPIO pins

to the hardware based Vector Interrupt Controller (VIC) that means these external inputs

can generate edge-triggered interrupts. All of these features make the LPC2468

particularly suitable for industrial control and medical systems.

LPC2468主要特性:

ARM7TDMI-S processor, running at up to 72 MHz.

512 kB on-chip flash program memory with In-System Programming (ISP) and

In-Application Programming (IAP) capabilities. Flash program memory is on the ARM

local bus for high performance CPU access.

98 kB on-chip SRAM includes:

64 kB of SRAM on the ARM local bus for high performance CPU access.

16 kB SRAM for Ethernet interface. Can also be used as general purpose SRAM.

16 kB SRAM for general purpose DMA use also accessible by the USB.

2 kB SRAM data storage powered from the Real-Time Clock (RTC) power domain.

Dual Advanced High-performance Bus (AHB) system allows simultaneous Ethernet

DMA, USB DMA, and program execution from on-chip flash with no contention.

EMC provides support for asynchronous static memory devices such as RAM, ROM

and flash, as well as dynamic memories such as Single Data Rate SDRAM.

Advanced Vectored Interrupt Controller (VIC), supporting up to 32 vectored interrupts.

General Purpose AHB DMA controller (GPDMA) that can be used with the SSP,

I2S-bus, and SD/MMC interface as well as for memory-to-memory transfers.

Serial Interfaces:

Ethernet MAC with MII/RMII interface and associated DMA controller. These

functions reside on an independent AHB.

USB 2.0 full-speed dual port Device/Host/OTG Controller with on-chip PHY and

associated DMA controller.

Four UARTs with fractional baud rate generation, one with modem control I/O, one

with IrDA support, all with FIFO.

CAN controller with two channels.

SPI controller.

Two SSP controllers, with FIFO and multi-protocol capabilities. One is an alternate

for the SPI port, sharing its interrupt. SSPs can be used with the GPDMA controller.

Three I2C-bus interfaces (one with open-drain and two with standard port pins).

I2S (Inter-IC Sound) interface for digital audio input or output. It can be used with

the GPDMA.

Other peripherals:

SD/MMC memory card interface.

160 General purpose I/O pins with configurable pull-up/down resistors.

10-bit ADC with input multiplexing among 8 pins.

10-bit DAC.

Four general purpose timers/counters with 8 capture inputs and 10 compare

outputs. Each timer block has an external count input.

Two PWM/timer blocks with support for three-phase motor control. Each PWM has

an external count inputs.

RTC with separate power domain, clock source can be the RTC oscillator or the

APB clock.

2 kB SRAM powered from the RTC power pin, allowing data to be stored when the

rest of the chip is powered off.

WatchDog Timer (WDT). The WDT can be clocked from the internal RC oscillator,

the RTC oscillator, or the APB clock.

Standard ARM test/debug interface for compatibility with existing tools.

Emulation trace module supports real-time trace.

Single 3.3 V power supply (3.0 V to 3.6 V).

Three reduced power modes: idle, sleep, and power-down.

Four external interrupt inputs configurable as edge/level sensitive. All pins on port 0

and port 2 can be used as edge sensitive interrupt sources.

图1.LPC2468方框图

建议的USB接口解决方案

图2.LPC2468和自有电源器件的USB接口方案

图3.LPC2468和总线供电器件的USB接口方案

图4.LPC2468 USB OTG端口配置方案:USB端口1 OTG双功能器件,USB端口2主器件

图5.LPC2468 USB OTG端口配置:VP_VM模式

图6.LPC2468 USB OTG端口配置:USB端口2从器件,USB端口1主器件

图7.LPC2468 USB OTG端口配置:USB端口1主器件,USB端口2主器件

更多计算机与外设信息请关注：21ic计算机与外设频道