DDR2 Write data generation with Native Interaface

Altera_Forum · ‎01-28-2010

Dear All,

Am using stratix III device, successfully generated DDR2 controller. I simulated the DDR2 with the example driver code generated by the tool. Chosen native Interface for read/write operation. As per the user guide write data has to presented in the clock cycle after the local_wdata_req signal is asserted.(Ref Page No 4-13 in (user guide emi_ddr_ug.pdf)

But in the example driver code, local_wdata_req was delayed by a clock cycle and write data is generated. This results first data is fed for two clock cycle. If i generate the data without any delay, i am missing my first data.

Please let me know why the local_wdata_req is delayed by one clock cycle.

Thanks in Advance.

Best Regards,

Cheevu

Altera_Forum · ‎01-29-2010

Well it's been quite some time since I looked at the example driver. But I believe delaying the local_wdata_req simply makes it look like an "ACK" rather than a request. So if your write data is ahead of the controller (meaning you're presenting it to the controller and just waiting for it to acknowledge) it may be easier to delay the signal and use it as an ack.

Jake