UM10208_2
© NXP B.V. 2007. All rights reserved.
User manual
Rev. 02 — 1 June 2007
4 of 362
NXP Semiconductors
UM10208
Chapter 1: LPC2800 Introductory information
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180 pin TFBGA package
3.
Applications
•
Portable, battery powered devices
•
USB devices
4.
Architectural overview
The LPC288x includes an ARM7TDMI CPU with an 8kB cache, an AMBA Advanced
High-performance Bus (AHB) interfacing to high speed on-chip peripherals and internal
and external memory, and four AMBA Advanced Peripheral Buses (APBs) for connection
to other on-chip peripheral functions. The LPC288x permanently configures the
ARM7TDMI processor for little-endian byte order.
The LPC288x includes a multi-layer AHB and four separate APBs, in order to minimize
interference between the USB controller, other DMA operations, and processor activity.
Bus masters include the ARM7 itself, the USB block, and the general purpose DMA
controller.
Lower speed peripheral functions are connected to the APBs. Four AHB-to-APB bridges
interface the APBs to the AHB.
5.
ARM7TDMI processor
The ARM7TDMI is a general purpose 32 bit microprocessor that offers high performance
and very low power consumption. The ARM architecture is based on Reduced Instruction
Set Computer (RISC) principles, and the instruction set and related decode mechanism
are much simpler than those of microprogrammed Complex Instruction Set Computers.
This simplicity results in a high instruction throughput and impressive real-time interrupt
response from a small and cost-effective processor core.
Pipeline techniques are employed so that all parts of the processing and memory systems
can operate continuously. Typically, while one instruction is being executed, its successor
is being decoded, and a third instruction is being fetched from memory.
The ARM7TDMI processor also employs a unique architectural strategy known as
THUMB, which makes it ideally suited to high-volume applications with memory
restrictions, or applications where code density is an issue.
The key idea behind THUMB is that of a super-reduced instruction set. Essentially, the
ARM7TDMI processor has two instruction sets:
•
The standard 32 bit ARM instruction set.
•
A 16 bit THUMB instruction set.
The THUMB set’s 16 bit instruction length allows it to approach twice the density of
standard ARM code while retaining most of the ARM’s performance advantage over a
traditional 16 bit processor using 16 bit registers. This is possible because THUMB code
operates on the same 32 bit register set as ARM code.