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What is the difference between M4 and MP series

O M
Note: This was originally posted on 8th July 2013 at http://forums.arm.com

Hello

[size=2]
[/size]

[size=2]I have to port a project that was written for the ARM11 MPcore to a project that will run on M4 (actually it is freescale Kinetis K60with M4 inside it)[/size]





[size=2]I saw in the documents of the ARM11 MP that it has 2 levelTLB, seven modes of operation (FIQ, IRQ, Supervisor, Abort, System, Undefinedmode), ...[/size]



In the documentation for the M4 I don't find any of it.



May I ask if it is exist in the M4 (K60) and what is themain differences between those two processors ?



Thanks a lot

  OM

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  • Arm Employee Badge
    Note: This was originally posted on 9th July 2013 at http://forums.arm.com

    [color=#222222][font=Arial, Helvetica, sans-serif]> 2. I wasn't aware of Thumb2 instruction set.[/font][/color] Is the integer type is 32 bit or 16 ?

    The Cortex-M family are still all 32-bit cores, so the register size etc is still 32-bits. Thumb introduces some 16-bit instructions, but they still operate on 32-bit data registers.

    > If it is 32 bits, does the access to it is in one cycle or two ?

    From the instruction set side of things each register load is a single instruction. Bus cycles depend on the implementation. It is quite common for external ROM or Flash to only have an 8 or 16-bit data bus to reduce pin-out on some MCU designs, so 32-bit accesses take multiple cycles, but this is all managed in hardware. Internal memory inside the MCU is normally using a 32-bit data path, but not always.

    ARM only design the CPU core, so for full device memory system specifications you will need to check with a specific manufacturer.

Reply
  • Arm Employee Badge
    Note: This was originally posted on 9th July 2013 at http://forums.arm.com

    [color=#222222][font=Arial, Helvetica, sans-serif]> 2. I wasn't aware of Thumb2 instruction set.[/font][/color] Is the integer type is 32 bit or 16 ?

    The Cortex-M family are still all 32-bit cores, so the register size etc is still 32-bits. Thumb introduces some 16-bit instructions, but they still operate on 32-bit data registers.

    > If it is 32 bits, does the access to it is in one cycle or two ?

    From the instruction set side of things each register load is a single instruction. Bus cycles depend on the implementation. It is quite common for external ROM or Flash to only have an 8 or 16-bit data bus to reduce pin-out on some MCU designs, so 32-bit accesses take multiple cycles, but this is all managed in hardware. Internal memory inside the MCU is normally using a 32-bit data path, but not always.

    ARM only design the CPU core, so for full device memory system specifications you will need to check with a specific manufacturer.

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