today,I am debuging a DM6437 Board,which is our custom board .It's Logic is like TI's DM6437 EVM.The difference between out board and TI evm is ：
1 ddr2 part number：hy5ps1g1631---mt47h32m16
2 ddr2's CTRL BUS and DATA BUS 's serial resistor(22 or 33 ohm) in our board is removed all( is done when desinging logic).But TI EVM remaining.
3 power chip is different，but voltage and amp is right。power on sequence is ok，also。(3.3 1.8 1.2)
other difference does not involve ddr2.
Then,I meet the problem : ddr2 can not access!
Write or Read,is not WORK
Using CCS ,I can read ddr2 's data is all 0xffffffff,it changed to 0x0 if I write any value into ccs window
Using oscilloscope ,I can watch the data bus 's voltage is holding about 1.0V.and DQS、ADDR signal。
note：DDR2 congfiguration is updated，include bank、page、timing。
note：I have two boards，one board ddr2 had ever work ok once，when it is first powered on。but never ok again
IT is a big trouble ，Who can help me？
thank U
