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MPC5777C FEC Module Cannot connect to other device

Question asked by Luke Zhang on Feb 20, 2019



I'm trying to implement the ethernet module (FEC) using MPC5777c 516DS and MPC57xx Motherboard. I'm choosing RMII mode I'm referring the example code from AN4577 and the MPC5777M FEC example.


I used 2 ways to test it:

1. I'm using an external RJ45 loopback tester with TX and RX connect together and plug it in. The module works fine and the receiver can receive what the transmitter sends. The activity LED blinking but the link LED never turn on.


2. This time I connected 2 motherboards together with an Ethernet cable, both of chips program with the same code. But they are not communicate with each other, both stuck at isConnected(), which is used for checking "Link Status" bit and my link status bit is always 0.


Here's the function of isConnected()


int16_t isConnected()
   return 1;

   uint16_t data;
   int16_t result = 0;

   if (miiRead(0x0001, &data))
      result = (data & 0x0004) ? 1 : 0;


   return result;


My hardware jumper configuration is:

  • 516DS:

      J25   - 12

      J524 - 12

      J510 - 23

      J26   - 23

  • Motherboard:

      J61 - 12

      J63 - 23


The code I'm referring is from 

Need sample code MPC5777M Fast Ethernet Controller to communicate TJA1100 NXP  PHY This link.