FSMC- BUSY or HOLD Type Interface Activity for DPRAM

jschatz · ‎2009-07-15

Posted on July 15, 2009 at 16:25

jschatz · ‎2011-05-17

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 · ‎2011-05-17

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.

martindavey9 · ‎2011-05-17

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.

jschatz · ‎2011-05-17

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.