• State Not Answered
  • Locked Locked
  • Replies 5 replies
  • Subscribers 348 subscribers
  • Views 17997 views
  • Users 0 members are here
Options
Related
How was your experience today?
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

ITCM, DTCM and IRAM access

Mallikarjun Shivappa Bidari
Note: This was originally posted on 28th March 2012 at http://forums.arm.com

Hi,

The ITCM and DTCM are used to improve the performance or the access speed (Low latency memory and Unpredictibility of the caches).
Similarly the IRAM also provides the improved speed.
If the system has both IRAM and TCM, then how does the IRAM and TCM access differ (Where does IRAM and TCM connected, is it on system bus)?


Regards,
Malli
  • 0
    Note: This was originally posted on 2nd April 2012 at http://forums.arm.com


    TCMs are connected directly to the processor, not through the bus.  So you don't have bus arbitration or the overhead of the bus protocol when you speak to them.


    thank you.
    But how about the IRAM? is it connected on the System bus or directly to the processor? if it is on the System bus, how is different from the SRAM or other flash memory connected on the system bus?
    If the TCMs are connected to processor, do they still use the addresses which fall within the 2 pow 32 range?
  • 0
    Note: This was originally posted on 2nd April 2012 at http://forums.arm.com

    IRAM is an Internal RAM. In most of the SOC, we usually have IRAM of size 128KB or 64KB etc... This is usually termed little faster than the SRAM access.
    So need to know how this IRAM is different from TCM memory interms of connection and access.
  • 0
    Note: This was originally posted on 2nd April 2012 at http://forums.arm.com

    Ahh ok, that makes sense.

    So TCMs are memories connected directly to the processor.  They also typically (but not always) fast - that is the same or near processor frequency,

    IRAMs in your case are just means on SoC memory.  It'll still be connected through the bus.  In terms of speed, typically much quicker than the bulk off-chip memories.  But probably still lower frequency than the processor itself.  As the bus usually runs at a lower frequency than the processor.

    IRAM vs TCM
    The main difference between them then is how the connect to the processor.  TCMs directly to the processor, and IRAMs through the bus interface.  What benefit this gives is system specific.  Typically its going to be that with TCMs there can be contention with other masters.
  • 0
    Note: This was originally posted on 30th March 2012 at http://forums.arm.com

    TCMs are connected directly to the processor, not through the bus.  So you don't have bus arbitration or the overhead of the bus protocol when you speak to them.
  • 0
    Note: This was originally posted on 2nd April 2012 at http://forums.arm.com

    I'm not sure what you mean by "IRAM" so will have to pass on that question.

    For TCMs, yes they fall into the standard address range of the processor.  What is different is how they physically connect to the processor.