ARM as replacement for 8051

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

Parents
  • "My understanding is that the ARM core has a 32 bit instruction set"

    It also has the 16-bit "Thumb" (sub)set.

    "8051 code (8 bit instruction set)"

    Actually, the 8051 has an 8-bit Word Size - not all instructions are 8 bits!

    "what would the expected size of program code be for the ARM target relative to that of the 8051 (bigger/smaller/indeterminate)?"

    Almost certainly bigger - but memory is cheap these days.
    In fact, you'd have a job finding a ROM of only 64K these days - it's not the size of the ROM that's the problem for 8051s!

    "Assuming it's possible for ARM based devices to fetch instructions from external flash"

    Why specifically external flash?
    There are plenty with on-chip flash - see:

    http://www.keil.com/dd/search_parm.asp

    http://www.keil.com/books/armbooks.asp

    and, of course, http://www.arm.com

    Why not talk to your local distributor?
    Many of them offer introductory courses/seminars - often free!

Reply
  • "My understanding is that the ARM core has a 32 bit instruction set"

    It also has the 16-bit "Thumb" (sub)set.

    "8051 code (8 bit instruction set)"

    Actually, the 8051 has an 8-bit Word Size - not all instructions are 8 bits!

    "what would the expected size of program code be for the ARM target relative to that of the 8051 (bigger/smaller/indeterminate)?"

    Almost certainly bigger - but memory is cheap these days.
    In fact, you'd have a job finding a ROM of only 64K these days - it's not the size of the ROM that's the problem for 8051s!

    "Assuming it's possible for ARM based devices to fetch instructions from external flash"

    Why specifically external flash?
    There are plenty with on-chip flash - see:

    http://www.keil.com/dd/search_parm.asp

    http://www.keil.com/books/armbooks.asp

    and, of course, http://www.arm.com

    Why not talk to your local distributor?
    Many of them offer introductory courses/seminars - often free!

Children
More questions in this forum