i.MX7D LPDDR3 byte and bit swapping

[ko-hey]

Hi all,

Our customer have a question about i.MX7 LPDDR3 layout and they want to use byte swapping and bit swapping with LPDDR3, but there is no hardware design guide for i.MX7 to judge whether it is ok or not.

I found following thread but I can't understand clearly.

https://community.nxp.com/t5/i-MX-Processors/I-MX7-LPDDR3-DQ-swap-in-the-byte/td-p/627704

So would you give us advise whether they can use byte swapping and bit swapping or not for LPDDR3 with i.MX7?

Ko-hey

[weidong_sun · Accepted solution]

Hi, ko-hey,

   Actually, you can get more information from LPDDR3 protocol.  we didn't released i.MX7D LPDDR3 validation board, I have no more information about it.

But below is for you reference:

According to the LPDDR3 protocol, 32BIT data lines:
1. The first byte cannot be changed.
2. Other bytes can be swpped.
3. The first bit of each byte cannot be swapped.
such as:
---No.1 Byte:
CPU_DDR_D00----DDR_D00
...
CPU_DDR_D07----DDR_D07
---No.2 & No.3 Byte are swapped(FOR EXAMPLE)
CPU_DDR_D08----DDR_D16 (MUST)
CPU_DDR_D09~CPU_DDR_D15------>DDR_D17~DDR_D23( bits can be swapped)
CPU_DDR_D16----DDR_D08 (MUST)
CPU_DDR_D17~CPU_DDR_D23------>DDR_D09~DDR_D15

In order to ensure the correctness of the connection, please make further confirmation with the LPDDR3 manufacturer!

Hope above advice is helpful to you.

Have a nice day!

B.R,

Weidong