I can get the correct testcode 0x2000 from A channel output in Testcode mode.But it always be 0x2000 in normal Offset binary mode or 0x0000 in normal Twos complement mode.
I am sure the wave of differential input in A channel is correct(I get the signal from the demo board's input circuit，because the input circuit on my board is proved to be wrong).
The clock from the crystal is a kind of bad,so I removed it and connected 40MHz Single-Ended 1.8 V CMOS Clock directly form the Signal Generator,but it had no effect.
I'm a Chinese university student,so I sent an e-mail to China.Support@analog.com for help.Their first reply is to ask my company/school name!.After I told them,They suggested me to submit the problem to ez.analog.com or ezchina.analog.com.If I am from Tsinghua University or HUAWEI Inc, will there be any difference?(╯‵□′)╯︵┻━┻
It will help me a lot,if anyone can solve my problem.
This is the schematic:
CSB,SCLK/DTP and SDIO/DFS are connected to FPGA
This is my test project: