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jschatz
Associate III
July 15, 2009
Question

FSMC- BUSY or HOLD Type Interface Activity for DPRAM

  • July 15, 2009
  • 4 replies
  • 725 views
Posted on July 15, 2009 at 16:25

FSMC- BUSY or HOLD Type Interface Activity for DPRAM

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    4 replies

    jschatz
    jschatzAuthor
    Associate III
    May 17, 2011
    Posted on May 17, 2011 at 13:11

    I think I just stumbled onto my own answer to this question...

    There is a NWAIT line that could be tied and polarity selected to allow me to apply a temporary hold onto the ARM when a memory access (FSMC) is used.

    Since I have never used an ARM before, I have been finding there to be a huge amount of information to sift through to get to my final circuit. I am assuming that if there is a wait forced back into the FSMC that the timers and other internal non-FSMC operations will continue to run as normal.

    jschatz
    jschatzAuthor
    Associate III
    May 17, 2011
    Posted on May 17, 2011 at 13:11

    I am using the FSMC interface for external RAM per the app-note to operate an FPGA that has a memory map of functions in it.

    Part of my application involves the use of a DPRAM style interface to an external process. This DPRAM is being incorporated into my FPGA.

    To avoid collisions of memory access, DPRAMs use a BUSY line to hold their access if the other side of the DPRAM is being accessed.

    Is there a way to perform a HOLD or BUSY in the large model STM32 device?

    This would temporarily put the processor into a wait state to allow the external hardware to finish its access.

    jschatz
    jschatzAuthor
    Associate III
    May 17, 2011
    Posted on May 17, 2011 at 13:11

    I still connected the line in my circuit. They added the comment after my inquiry.

    Also, I heard that they are considering including the WAIT configuration in future revisions of the component for asynchronous FSMC operations.

    martindavey9
    Associate II
    May 17, 2011
    Posted on May 17, 2011 at 13:11

    Hi,

    Just to make you aware, recent STM32 reference manual indicates WAIT signal only used with syncronous memory.

    Martin.