How to adjust parameters of PCIe_PHY by changing the IOMUXC_GPR8 register ?

peteramond — Fri, 27 Dec 2019 09:16:30 GMT

Dear All,

Parameters of PCIe_PHY can be adjusted by changing the IOMUXC_GPR8 register settings as described in app note PCIe Certification Guide for i.MX 6 >> http://cache.freescale.com/files/32bit/doc/app_note/AN4784.pdf

Hardware based on iMAX6Q

And I'm using PCIE Gen 1.

In this documentation (See bellow) we can see;

Bit 31-25 represent 7'hxx TX launch amplitude swing_low value.

Bit 5-0 represent 6'hxx Gen 1 de-emphasis value.

When I measure the swing low and de-emphasis values from the eye diagram I got;

swing low = 400mV

de-emphasis = 3.5dB

Now I have to put above values to my GPR8 Register = 0x020e0020

Could you please tell me how to put above two values to this register according to it's bit pattern ? I couldn't see any documentation in NXP for this.

Regards,

Peter.

Re: How to adjust parameters of PCIe_PHY by changing the IOMUXC_GPR8 register ?

igorpadykov — Tue, 31 Dec 2019 00:45:43 GMT

Hi Peter

I am not aware of additional documentation on this subject, but seems

one can try to test with low and high limits of register settings then make evaluation.

Best regards
igor
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topic How to adjust parameters of PCIe_PHY by changing the IOMUXC_GPR8 register ? in i.MX Processors

How to adjust parameters of PCIe_PHY by changing the IOMUXC_GPR8 register ?

Re: How to adjust parameters of PCIe_PHY by changing the IOMUXC_GPR8 register ?