The data manual for the F28335 (sprs439f) shows that with Zone 6 and Zone 7 you could potentially add up to 2MX16 of off-chip RAM. The ControlCARD pinout table labels 9 pins with "EMIF" (External Memory Interface: XD16-21, XD30-31, XREADY).
Could you provide an example of an external RAM chip that could be used with the ControlCARD and briefly explain what connections are necessary?