Atxmega + SDRAM

[Cyborg666]

Hi!

I'm working on a project with my brother, in which he will do the electronics, and I will do the programming.
We need quite a bit of RAM for this project, and I was wondering if it's possible to use this micro in conjunction with this RAM?

http://www.mouser.com/ds/2/36/Atmel-8385-8-and-16-bit-AVR-Microcontroller-ATxmeg-259120.pdf
http://www.mouser.com/ds/2/12/64M-AS4C4M16S-7450.pdf

Does anyone have some tips on how to hook them up properly, or perhaps a link to a guide or something?

[amyk]

That SDRAM specifies no minimum clock frequency (they usually have one), but it must be refreshed at least every 15.6us. Either way, interfacing SDRAM to an 8-bit MCU is not an easy task, although it can be done.

[Psi]

The xmega has an external SRAM/SDRAM bus, so there should be no problem using SDRAM.
However you will need to make sure the SDRAM IC timing is within the xmegas external bus timing.

[David Hess]

. . . interfacing SDRAM to an 8-bit MCU is not an easy task, although it can be done.

That is actually FPM or EDO asynchronous DRAM and not synchronous DRAM which was not used in 30 pin SIMMs.  It is being accessed using programmed I/O so it is only suitable for use with emulation which is exactly what the author is doing.

Cyborg666, that microcontroller only has an 8 bit wide SDRAM interface so it should work but half that that 16 bit wide memory would be lost.

[theatrus]

Do note that AVR-GCC does not work in the hybrid addressing mode required to access all of your memory on the xMega. You can do assembly-assisted-copying, or use IAR or another compiler which does support it.

[janoc]

The xmega has an external SRAM/SDRAM bus, so there should be no problem using SDRAM.
However you will need to make sure the SDRAM IC timing is within the xmegas external bus timing.

There is an appnote on it: http://www.atmel.com/images/doc8058.pdf

However, XMega doesn't have a dedicated SDRAM controller, the appnote only shows how to drive the SDRAM electrically. All the initialization and everything else that an SDRAM needs is up to you to do in software (the refresh can be handled by the EBI on the chip). Not an easy job for an 8bit micro, not to mention that you would block most of the available I/O with it.

I would probably look for something beefier if SDRAM is needed - e.g. an ARM.

[Cyborg666]

You haven't been very specific about how much RAM you need, how fast you need to access it, and how you need to update it. I am inclined to want to ask why you must combine an Atxmega and SDRAM. In this day it seems to be a better choice to choose some more suitable platform where you are less constrained by the device limitations.

We're trying to make a digital audio delay pedal for guitar players.
It's supposed to have a feature in which you can record a sample of about 40 seconds - in stereo.

I've only worked with arduino before, and have mostly done regular PC-programming. So I'm a bit worried about how hard this will be.

Do you have any suggestions on which controller/memory would be suitable for these tasks?

[Tubis]

Hi. Im the other part of this experiment. I understand nothing about programing but i can hook up the electrical and make pcb.

We selected the atxmega because it had adc and dac and enought pins for a number of external controls in form of potentiometers pushbuttons, rotary switches and to control some leds and analog bypass line. The project is to produce something like this: http://www.bossus.com/gear/productdetails.php?ProductId=958&ParentId=255

Would this memory work better? http://se.mouser.com/ProductDetail/ISSI/IS42S81600E-7TL/?qs=sGAEpiMZZMti5BT4iPSEnXRShtGGCFK3TG42wTPCEQU%3d

It looks more pin compatible?