Showing results for 
Search instead for 
Did you mean: 
Valued Contributor III

How to measure driver impedance of output drivers in OCD calibration for DDR2



I am implementing Off-chip driver calibration in the DDR2 memory controller design on Altera Cyclone III EP3C120 board and am struck in the drive mode. Drive mode is used to measure the DDR-SDRAM output driver impedance. 


The DDR2 specs have mentioned to use any external device or the memory controller to measure the voltage level of the output signals (DQ, DQS, and /DQS) and 

determine whether or not the pull-up/pull-down resistance is at the target value. 


Is there any way this can be achieved sensing the DDR I/O cells on the board and implement it in the RTL? 

Any related input is highly appreciated. 


Thanks in advance.
0 Kudos