Upgrading to the Architecture for tomorrow's Digital World
Design migration from the ARM7
The ARM7 family is the world's most widely used 32-bit embedded processor family, with more than 170 silicon licensees and over 10 Billion units shipped since its introduction in 1994.
While the ARM7 processor family continues to be used today for simple 32-bit devices, newer digital designs are increasingly making use of the newer, more powerful and feature-rich ARM processors which offer significant technical enhancements over the ARM7 family.
System designers wishing to upgrade from ARM7 benefit from a robust ARM processor roadmap providing multiple upgrade options, including the latest Cortex processors.
In most cases migration is straightforward, and brings significant benefits in PPA, features and efficiency.
The table below presents the most common upward migration paths for adapting current ARM7 based designs for the next generation.
| Current processor | Upgrade driver | Alternative ARM processors | Benefits of upgrading |
|---|---|---|---|
| ARM7TDMI-S | Application upgrade | ARM926EJ-S, ARM968E-S, Cortex-A Series |
|
| Cortex-R Series |
| ||
| Socket upgrade | Cortex-M0 |
| |
| Cortex-M3 |
| ||
| ARM7EJ-S | Application upgrade | ARM926EJ-S |
|
Upgrading options from ARM7TDMI-S for the Embedded market
For ARM7TDMI-S users in the embedded market, the Cortex-M0 and Cortex-M3 processors offer a much superior alternative, enabling tomorrow's embedded applications by delivering more features at a lower cost, increasing connectivity, better code reuse, and improved energy efficiency.
| Features | ARM7TDMI | Cortex-M0/M3 | Benefits of upgrading |
|---|---|---|---|
| Interrupt controller | No standard interrupt controller | Integrated Nested Vectored Interrupt Controller (NVIC) | Flexible and powerful interrupt handling |
| ISR entry | Non-deterministic ISR entry | H/W stacking ensures deterministic ISR entry | Fully deterministic interrupt handling |
| Power management | No in-built power management | Architected sleep mode support | Extremely low power modes |
| Need for assembly language code | Assembler code required (for ISR etc) | No assembler code required |
|
| Instruction set Performance v/s Code size | Optimal performance-code size balance requires interworking between ARM & Thumb code | Thumb-2 offers ARM performance at Thumb code density |
|
| Ease of application porting from one device to another | Lack of standardization inhibits application porting | NVIC, SysTick & Memory Map defined CMSIS Compatible |
|
For advice on porting software written for the ARM7TDMI-S to the Cortex-M3 processor, please read the whitepaper "ARM Cortex-M3 Processor Software Development for ARM7TDMI Processor Programmers"
For a detailed comparison between ARM7 family processors and the latest ARM alternatives, please use the Processor Selector.
