A question about SDRAM's refresh!

Probably not. The other rows would probably discharge without refresh.

Also, check that there is no upper limit on the row-select time - 1 second is an awfully long time.... I know there used to be maximum tRAS specs on old-style DRAMS, I think for power dissipation reasons. Looking at a Micron datasheet I have to hand, they show a maximum ACTIVE to PRECHARGE time of 120uS, so a 1 seond burst would be well in excess of this.

Why would you want to burst-write for 1 second anyway - you can only write within that row so there's a limit to how much data you can store...!

To follow on Mike's comment, I think you'll find the burst has a max length. 4096 IIRC from Micron's sheet. You can activate refresh between bursts.

If you're writing for a full second, there's got to be a lot of dead time in there, and you should be splitting up the bursts and enabling refresh in between writes.

And you didn't mention - SDR or DDR? What chip are you using for reference?

Richard

If the device has concurrent precharge then you should be able write continuously as long as you write say in bursts of 4 or 8 in sequentially different rows or banks with auto-precharge. Normally it's a matter of mapping the "incremental address" of your counter to row, column and bank addresses.