Dear Sir
Customers use the i.MX6DL ENET with RGMII.
Please tell me about RGMII I/F.
The following explanation is on P146 of IMX6SDLIEC Rev.8.
ENET_REF_CLK is used as a clock source for MII and RGMII modes only.
RGMII mode uses either GPIO_16 or RGMII_TX_CTL as a clock source.
For more information on these clocks, see the device Reference Manual and the Hardware Development Guide for i.MX 6Quad, 6Dual, 6DualLite, 6Solo Families of Applications Processors (IMX6DQ6SDLHDG).
I confirmed the Table 23-1. ENET External Signals (P1062) of IMX6SDLRM Rev.4.
ENET_REF_CLK : In RMII mode, this signal is the reference clock for receive, transmit, and the control interface.
(It seems that the ENET_REF_CLK is used only when the MII setting.)
Q1.
Does it need the 125MHz clock to ENET_REF_CLK when it is configured the ENET as RGMII?
Q2.
How is the AC spec (Duty) if it needs the 125MHz clock to the ENET_REF_CLK?
Best Regards,
Eishi SHIBUSAWA
Hello Eishi SHIBUSAWA,
To answer your first question RGMII does require a 125MHz clock externally provided.
You can find more details regarding this on Table 2-9 of the i.MX6 Hardware Design Guide.
As for the duty cycle the recommendation is to use good (25-50 ppm) frequency stability and 45%~55% & duty cycle clock source.
I hope this helps!
Regards,