KJ wrote:
> <[email protected]> wrote in message
> news:[email protected] oups.com...
>> Hi,
>>
>> I'm trying to control a SDR SDRAM (Micron 64Mbit chip) using an Altera
>> DE2 board. I've gotten the hardware interface squared away (thanks
>> everyone for your help!).
>>
>> Now it's the tricky stuff. Any one have an idea how I can change the
>> refresh rate while the RAM is in operation?
>>
> The most obvious question would be 'Why?'
>
>> I have the DRAM interface built using the SOPC builder that comes with
>> Quartus II using the NIOS II system.
>>
> That will limit your options (as would probably most other vendor IP DRAM
> controllers).
>
>> I know you can change the refresh rate during the build but I need a
>> way to change the refresh rate during operation. The only thing I can
>> think of is maybe change the clock speed? I have it running off a
>> 50Mhz clock....
>>
> A simpler way would be to simply have a DRAM controller that has an explicit
> 'Refresh Request' input that would cause the controller to perform a
> refresh. Then connect that input up to any programmable timer or other
> logic that you would like to use. Changing the clock rate would be far down
> on my list of ways to accomplish your goal....but again, it begs the
> original question about why you would want to change the refresh rate
> dynamically at all.

Assuming he has a good reason to change it,
the safest thing to do would be to call a
routine in flash to change it.