DDR2 Different Layer Layout

[avionicsman]

Hi everyone;
I need help for DDR2 Layout. I look at your DDR2 spreadsheet and video. But i didnt understand some point about design. My design is very simple. I have 1 CPU 1 DDR2 Ram. You can see my question below;
·Can I use diffrent layer for same signal groups? (E.x. A0 and A5 in different layers but A0 and DQ1 same layer.)

Some design sheet same signal groups will be in same layer , some design sheet same signal groups can be use different layer. (And both of them will be matched length.)

I send my RAM-CPU design pictures. They haven’t match right now.

I used 3 diffrent layers for RAM signals. But I used for different layers for same signal groups. What are you think about that, whats your suggestions?

Regards.

[robertferanec]

I had a look at the pictures. I am not sure. I have never done memory layout this way and I would not do memory layout this way, but that is just my opinion. However, I know that some companies and some people do not route groups same way and their boards still work just fine.

PS: I am not sure how the memory in your project is used and how fast it is, but usually I am very careful as failing memory usually means, that the whole board is not going to work and PCB has to be redesigned (that is in the case when you are running OS from DDR).

[avionicsman]

Thank you for reply. Probably i will use different layers and i will share results.

[avionicsman]

It works!!!

[robertferanec]

Congratulation