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Why doesn't use PCIE Gen 1 recommendation in Freescale SabreSD board ?

Question asked by Peter Amond on Oct 4, 2018
Latest reply on Oct 10, 2018 by igorpadykov

Hi All,

 

When I go through in Hardware design check list I could see following.

 

 

But when we refer Freescale Sabre SD board we can't see those changes. It should be both 470 Ohms and 56 Ohms pull up and pull down resistors for PCIE REFCLK.

 

In Freescale SabreSD board

 

 

 

In NXP iMAX6Q hardware design checklist.

 

 

1) Could you please explain why freescale is not using those changes ?

2) Why we need to use LVDS port for PCIE clock ? Is this a fault from NXP ? Any possibility to don't work or not getting stable PCIE link even without using recommended hardware settings (Pull up and pull down) ?

3) Why we use both pull up and pull down ?

 

Regards,

Peter

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