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ARM Cortex ICode, DCode, System buses

Felix Varghese
Note: This was originally posted on 26th February 2009 at http://forums.arm.com

I'm a bit confused about the bus structure and memory model of ARM Cortex M3. First of all, does Cortex M3 actually have 3 physically separate buses coming out of it?
They say that an instruction fetch in the code memory is over the ICode bus and data fetch is over DCode bus. So if i have some flash memory mapped into code memory region, which is used to store my code and some constant data, then how exactly would i connect the two buses to it? Would i connect two Code buses to the same physical IC?
And if i have a RAM chip mapped to the SRAM memory region used to hold my normal data, would i connect the system bus to it so i can perform normal data fetches over it?
Parents
  • 0 in reply to Simon Craske

    You said that  I-code and D-code bus work as the same, so implementor can improve the performance of system  by using such as way

    1. Simple arbiter (matrix) into a single slave (Flash/ROM/RAM).

    But I'm confused that 

    1.  CM3 consists with I-code , D-code bus. Why? then Can I use only one bus between I, D code bus?

    2.Could you let me know more detail about how can make a system improvement by Simple arbiter

Reply
  • 0 in reply to Simon Craske

    You said that  I-code and D-code bus work as the same, so implementor can improve the performance of system  by using such as way

    1. Simple arbiter (matrix) into a single slave (Flash/ROM/RAM).

    But I'm confused that 

    1.  CM3 consists with I-code , D-code bus. Why? then Can I use only one bus between I, D code bus?

    2.Could you let me know more detail about how can make a system improvement by Simple arbiter

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