Hi, there,

I planning to use SDR SDRAM (PC DIMMs) with our board, based on AT91RM9200 micro. However, there is a problem with width of data buses of at91 sdram controller(32 bit) and DIMM modules (64 bit). Maybe, someone knows the solution for this situation.
I know that much easy, to use 32bit bus width with SDRAM, but we need the system based on DIMMs. Thus, user can plug in any amount of SDRAM memory(up to 256MB), that he needs.

As far as i know, a most (?) of DIMM modules have SPD chip, which contain timings and numbers of col and rows. Is it possible to read this info (and eliminate the need for user input of those parameters)?

Thanks
Valen

Hi Valen,

Find in attach the PC133 SDRAM Specification Standard. Of course, it is possible to use DIMM module as SDRAM mass memory: it is a low cost and easy mean to add memory with our AT91RM9200 µC.
You have to use this spec only if the targeted module is compliant with this.
In this spec, page 21, you are going to find encoding description of the on-board EEPROM.

Hope this helps.

Thanks for answer!

As far as i understand, there is no reason to use PC133 DIMM's. Because master clock (and thus SDRAM controller) runs at 60...80Mhz. So, probably, PC66 is good enough.
But ,it is easier to purchase PC133 modules, rather than obsolete PC66.
(The difference in the price is not great)

Valen

Hello Valen,

God made little apples, there is no reason to use up to pc133, pc66 is enough.
The AT91RM9200 used with standard DIMM module could be a very good typical reference design for other users.
I am in vacation now and I think do not have free time as soon as I am going to return to work (the AT91SAM product line is in starting block), but I am going to think about this paper.
Do not hesitate to help me for this paper.

Sorry disturbing you, but are you ready w/ the paper ??