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How to change the 1588 PTP reference clock to fpga_ptp_ref_clk in Cyclone V


Hi I am using  FAMILY  Cyclone V  DEVICE 5CSEBA6U23I7 in my design and I an using linuxptp to tune the external PLL, in the first stemp I want to use the fpga_ptp_ref clock from FPGA side, 

I tried to use 0xFFD08060  regiater to change  the source of the 1588 PTP reference clock to fpga_ptp_ref_clk  by writing 0x36 tot he location (default was 0x6) after connecting the 50 MHz clock to hps_0_emac_ptp_ref_clock_clk  which is stopping the ToD counter, Is this the right way to change the PTP reference clock? If I change the  0xFFD08060 to 0x6  ToD starts counting with osc1_clk,

what is the right way of changing the 1588 PTP refernce clock?

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I figured out that we need to enable the signal from FPGA side to emac by  setting 0xFFD08028 =0xD , by this Signals from FPGA fabric can potentially affect operation of the EMAC module

If you want to change the PTP refeernce clock  then you need to  set

0xFFD08028 =0xD

0xFFD08060  =0x36