> Can I interface just 32 bit DDR4 with ECC memory to LS1046A.
Yes.
> Could please provide references in this regard.
Please refer to the FRWY-LS1046A schematics available at:
https://www.nxp.com/design/qoriq-developer-resources/ls1046a-freeway-board:FRWY-LS1046A?fpsp=1#Desig...
For 32-bit case do not implement U17 and U18.
Assuming that Accumulated ECC will be enabled, D1_MECC[4-7] have to be left unconnected.