25M clock for RGMII_TXC from IMX6Q internal

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25M clock for RGMII_TXC from IMX6Q internal

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youjinliang
Contributor I

Our project use BCM89810 ethernet phy on imx6Q and use android5.1. Because bcm89810 don't have reference clock output. bcm89810 run on RGMII mode at 100Mbps speed, it need 25M clock RGMII_TXC from IMX6Q.  How can I use internal 25M clock for RGMII_TXC. On IMX6q spec, there is a way to use GPIO_16 to get the 125M ENET_REF_CLK, but we don't use this pin. How can I setup to get the 25M clock for RGMII_TXC from imx6q internal? thanks

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art
NXP Employee
NXP Employee

RGMII_TXC is the output signal, generated internally by the ENET controller from the reference signal. For the RGMII mode, the 125MHz reference signal can be provided either externally through the ENET_REF_CLK pad, or internally. For the information on how to provide the reference clock internally, please refer to the Section 12.4.1 "Using the GPIO_16 pin to generate the reference clock" of the i.MX6 series Hardware Development Guide document, available on the i.MX6Q Documentation web page:

http://www.nxp.com/products/microcontrollers-and-processors/arm-processors/i.mx-applications-process...

Also, to get the 125MHz clock output, you have to set the CCM_ANALOG_PLL_ENETn[1:0] bits to 0b11.


Have a great day,
Artur

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