DP83822I: Using two DP83822 EVM board comminicate, but there are some problems.

Part Number: DP83822I
Other Parts Discussed in Thread: DP83822EVM

Hi team,

I do a test in our two EVM boards, like below pic1. There are two board, named board 1# and board 2#. This test need you confirm some question.

This is my test step:

1. After two board connect successfully, I let board 1# TX_EN and TXD3 keep high, which means board 1# will keep send the same package “0x1000”;
2. I test board 2#,  and I can catch the package “0x1000” by scope, I can test the RXD3 pin is high, like below pic2. ( pink one RXD3 signal, and Blue one is RXCLK) ;
3. At that time, I still let board 1#  keep TX_EN high but let the TXD3 change to low. But I test board 2#,  RXD3 signal still keep high rather than low. I don’t know why?
4. And I trigger  board 1#  TX_EN and keep TXD3 to low,  and find board 2#,  RXD3 signal go to low.
5. And I change  board 1# TXD3 to high again and trigger  board 1#  TX_EN,  and find board 2# RXD3 signal go to high from low. It seems to be normal. 

Do you have any suggestions for below situation?

Why does not board 2# RXD3 signal real time changed when board 1# TXD3 change?

 Why does it need trigger TX_EN when TX data changing?

pic1:

Pic2:

Best Regards,

Eggsy