Hi Sriram:
MQX provides external flash driver (flashx). You only need to configure FlexBus in order to communicate with your external memory. You must calculate the time your memory needs for read and write cycles to do this.
Once you configure Flexbus flashx driver usage will be transparent for the user.
You must consider 2 things.
1) MQX configures Flexbus is BSP by default. This configuration is set to communicate with external MRAM. You must be sure that you are not keeping any default configuration that may impact your memory.
2) Check in the Linker Command File (LCF) the addresses that are used for external memory because the driver will look for these addresses.
Hope this information helps!!!
Sol