Swapping DDR3 pins to FPGA

[aminpix]

I am trying to connect a two DDR3 to a Zynq FPGA. I need to swap some pins for DDR constrain purpose.
I had swap some data pins with some DDR_DMx pins as shown in the pictures.
DDR_DQxx are data pins and DDR_DMx are connected to DM pins.

The following pin connections are good or not?

 

[barry]

I need to swap some pins for DDR constrain purpose.

I don't understand that comment at all. The manufacturer has specified specific pins for specific functions, but you need to swap them?

 

[aminpix]

Yes, to rout the data signals and make them same length, sometimes we need to swap the pins. I am not sure if I can swap DDR_DMx pins with DDR_DQxx or data pins or not?

 

[barry]

I’m pretty sure you can’t swap DQ and DM. But you don’t need to swap pins to equalize length: you use length tuning.

 

[dpaul]

@aminpix
I would never ever play around with dedicated DDR* pins. Please stick to dedicated pins if you wish the DDR* interface to operate correctly.

 

[barry]

@aminpix
I would never ever play around with dedicated DDR* pins. Please stick to dedicated pins if you wish the DDR* interface to operate correctly.

Agreed. There’s no reason to swap these pins.

 

[aminpix]

I know we can swap DDR_DQxx pins as long as they belong to the same byte group. For example we can swap DDR_DQ06 and DDR_DQ07 because they belong to the same byte group (DDR_DQ00 to DDR_DQ07). But we can not swap DDR_DQ06 and DDR_DQ09.

We usually swap these pins to make PCB routing easier or even make it possible.
I am not sure if we can swap DDR_DQxx with DDR_DQM0 or not?

 

[barry]

I give up.

 

[pbernardi]

You are right when you say you can swap DDR_DQxx inside the same group, but you cannot swap any of DDR_DMxx pins (with DDR_DQxx or other DDR_DMxx).