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25MHz clock from i.MX 6 GPIO16?

Question asked by mahi on Jul 28, 2015
Latest reply on Jul 29, 2015 by Wigros Sun

Hi Community,

 

there are several posts about using the ENET-PLL to generate the 125MHz RGMII reference clock. But when doing this, I still need a crystal for the Ethernet PHY.

So I am considering using GPIO16 (mux configured for ENET_REF_CLOCK) as 25MHz clock output for the Gigabit-Ethernet PHY which itself provides the 125MHz reference clock for the RGMII.

 

A configuration like in Re: Using i.MX6 to generate 125MHz reference clock for RGMII interface  with the different DIV_SELECT = 00 for the PLL should do it.

 

The voltage levels of GPIO16 and the PHY's clock input are compatible.

 

 

Are there any pitfalls I didn't see yet?

What about jitter - may this be a problem? I can't find further information about the PLL.

 

 

Best regards

Martin

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