Question about data group DRAM_ADDR_CTRL in project iMX6 RexV1I1.
Khai , 09-28-2016, 01:40 AM
Hi Robert and everyone,
I have a question about the length in data group DRAM_ADDR_CTRL.
Why the length in data group DRAM_ADDR_CTRL is not same?
I have a question about the length in data group DRAM_ADDR_CTRL.
Why the length in data group DRAM_ADDR_CTRL is not same?
robertferanec , 10-01-2016, 07:23 AM
When doing length matching, you are looking at PIN-to-PIN distance. The total distance of track is irrelevant.
When you are doing length matching of Data signals, the total length will be basically the PIN-to-PIN length. However, once you split track and you create branches, total length is totally different from what you need and therefore the length between signals is not the same. What you need is to have a look at its distance between CPU and individual memory chips (CPU-to-MEM1, CPU-to-MEM2, CPU-to-MEM3, CPU-to-MEM4) - this is what needs to be the same.
In the latest Altium(s) you can create xSignals. They will help you to calculate the right distance, this video may help you: Altium – How to use xSignals ( in Fly-By, T-Branch + Other useful things )
When you are doing length matching of Data signals, the total length will be basically the PIN-to-PIN length. However, once you split track and you create branches, total length is totally different from what you need and therefore the length between signals is not the same. What you need is to have a look at its distance between CPU and individual memory chips (CPU-to-MEM1, CPU-to-MEM2, CPU-to-MEM3, CPU-to-MEM4) - this is what needs to be the same.
In the latest Altium(s) you can create xSignals. They will help you to calculate the right distance, this video may help you: Altium – How to use xSignals ( in Fly-By, T-Branch + Other useful things )
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