How can MPC5748G output RMII REF_CLK clock with 50HMz?

[hirofeng]

MPC5748G is connected to SJA1105S with RMII. But SJA1105S can not provide 50MHz REF_CLK.

My question is how to config MPC5748G to output RMII REF_CLK clock?

I use S32 studio  2017 R1 SDK with ProcessorExpert tool. 

[PetrS]

Hi,

RMII REF_CLK is only an input and clock cannot be generated on this pin.

The clock can be generated on CLKOUT_0/CLKOUT_1 pins where several internal clock sources can be selected. See more in chapter 9.4.6 CLKOUT clocking of the RM.

BR, Petr

[hirofeng]

Hi Petr,

   Thanks for your response!

   Now I am using NXP's dual chip EVB : LFGTWSEM.

  But according to its hardware schematic，there is no 50MHz clock source provided for both MPC5748G and SJA1105S.  Is there any mistake for this EVB? 

   Could you please help me check it? Thank you!

[PetrS]

Hi, 

as per schematic I understand MPC5748G PG1 pin (RMII REF_CLK) is connected to SJA1105's REF_CLK output (D1 pin). Probably this REF_CLK is able to provide 50MHz clock, however I do not know SJA1105 well. saa2003_53@ngs.ru‌

BR, Petr