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Hello,
We're considering an ARM based MCU as an alternative target to an existing 8051 based product, which leads me to ask some questions regarding the ARM architecture-
My understanding is that the ARM core has a 32 bit instruction set (typically), so asssuming a direct port of our existing 8051 code (8 bit instruction set) was possible, what would the expected size of program code be for the ARM target relative to that of the 8051 (bigger/smaller/indeterminate)?
Assuming it's possible for ARM based devices to fetch instructions from external flash (?), are there specific features that should be considered mandatory if the ARM device doesn't feature sufficient 'on-board' flash for program code/NVRAM (AMBA bus/SPI etc)?
Also if there's a resource that someone's aware of which deals with this level of detail, I'd appreciate a link, and any other comments/caveats regarding the ARM core...
Many thanks
David
Yes, there are plenty of devices with an external memory bus for flash or RAM. Atmel has new devices, NXP (Philips) has several devices, TI has devices. Keep in mind that this will run slower due to the speed of the flash and the extra time required to go off chip. On chip flash is often optimized to run the CPU at full speed like the NXP parts and the Cortex-M3 from Luminary.