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ARM7

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This article is about ARM7 processor cores. For the ARMv7-A and ARMv7-R instruction set architecture, see ARM architecture.
ARM7
Architecture and classification
Instruction setARM (32-bit).
ARM Architecture:
ARMv3.
ARM7T
Architecture and classification
Instruction setARM (32-bit),
Thumb (16-bit) (alternate).
ARM Architecture:
ARMv4T.
ARM7EJ
Architecture and classification
Instruction setARM (32-bit),
Thumb (16-bit) (alternate),
Jazelle (8-bit) (alternate).
ARM Architecture:,
ARMv5TEJ.

ARM7 is a group of older 32-bit ARM processor cores licensed by ARM Holdings.

Overview

File:Diagrama ARM7.jpg
ARM7 Block Diagram

This generation introduced the Thumb 16-bit instruction set providing improved code density compared to previous designs. The most widely used ARM7 designs implement the ARMv4T architecture, but some implement ARMv3 or ARMv5TEJ. All these designs use a Von Neumann architecture, thus the few versions comprising a cache do not separate data and instruction caches.

Some ARM7 cores are obsolete. One historically significant model, the ARM7DI[1] is notable for having introduced JTAG based on-chip debugging; the preceding ARM6 cores did not support it. The "D" represented a JTAG TAP for debugging; the "I" denoted an ICEBreaker debug module supporting hardware breakpoints and watchpoints, and letting the system be stalled for debugging. Subsequent cores included and enhanced this support.

It is a versatile processor designed for mobile devices and other low power electronics. This processor architecture is capable of up to 130 MIPS on a typical 0.13 µm process. The ARM7TDMI processor core implements ARM architecture v4T. The processor supports both 32-bit and 16-bit instructions via the ARM and Thumb instruction sets.

ARM licenses the processor to various semiconductor companies, which design full chips based on the ARM processor architecture.

Cores

Year ARM7 Cores
1994 ARM7DI
1995 ARM710a
1997 ARM720T
1997 ARM740T
1998 ARM710T
1998 ARM7TDMI
2001 ARM7TDMI-S
2001 ARM7EJ-S

ARM7

The original ARM7 was based on the earlier ARM6 design and used the same ARMv3 instruction set. The ARM710 variant was used in a CPU module for the Acorn Risc PC, and the first ARM based System on a Chip designs ARM7100 and ARM7500 used this core.

ARM7TDMI

The ARM7TDMI (ARM7+16 bit Thumb+JTAG Debug+fast Multiplier+enhanced ICE) processor implements the ARMv4 instruction set. It was licensed for manufacture by an array of semiconductor companies. In 2009 it remains one of the most widely used ARM cores, and is found in numerous deeply embedded system designs. Texas Instruments licensed the ARM7TDMI, which was designed into the Nokia 6110.[2] The ARM7TDMI-S variant is the synthesizable core.

ARM7EJ

The ARM7EJ is a version of the ARM7 implementing the ARMv5TE instruction set originally introduced with the more powerful ARM9E core.

Chips

Yamaha Super Intelligent Sound Processor has an ARM7 core
The Make Controller Kit with an Atmel AT91SAM7X256 (ARM) microcontroller.

Documentation

The amount of documentation for all ARM chips is daunting, especially for newcomers. The documentation for microcontrollers from past decades would easily be inclusive in a single document, but as chips have evolved so has the documentation grown. The total documentation is especially hard to grasp for all ARM chips since it consists of documents from the IC manufacturer and documents from CPU core vendor (ARM Holdings).

A typical top-down documentation tree is: high-level marketing slides, datasheet for the exact physical chip, a detailed reference manual that describes common peripherals and other aspects of physical chips within the same series, reference manual for the exact ARM core processor within the chip, reference manual for the ARM architecture of the core which includes detailed description of all instruction sets.

Documentation tree (top to bottom)
  1. IC manufacturer marketing slides.
  2. IC manufacturer datasheets.
  3. IC manufacturer reference manuals.
  4. ARM core reference manuals.
  5. ARM architecture reference manuals.

IC manufacturer has additional documents, including: evaluation board user manuals, application notes, getting started with development software, software library documents, errata, and more.

See also

References

  1. ^ "ARM7DI Data Sheet"; Document Number ARM DDI 0027D; Issued: Dec 1994.
  2. ^ Sakr, Sharif. "ARM co-founder John Biggs". Engadget. Retrieved December 23, 2011. [...] the ARM7-TDMI was licensed by Texas Instruments and designed into the Nokia 6110, which was the first ARM-powered GSM phone.
Wikimedia Commons has media related to ARM7 and ARM7TDMI.
ARM Holdings
Quick Reference Cards
  • Instructions: Thumb (1), ARM and Thumb-2 (2), Vector Floating Point (3)
  • Opcodes: Thumb (1, 2), ARM (3, 4), GNU Assembler Directives 5.
Other
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