C6678 最大能接多大的容量的nand flash? nand flash 接口必须走EMIF接口吗？

256MB的容量只针对使用地址线的异步Memory，Nand flash是不用地址线的，所以最大容量没有限制。这在EMIF user guide上有说明。

Note—The 64MB limit per chip select applies only for asynchronous memories
that use the EMIF16 address bus for addressing - typically ASRAM and NOR
flash. NAND flash uses the data bus as a multiplexed data/address bus and does
not use EMIF16 address pins for addressing (Only CLE and ALE signals use
the address bus. Refer to Section 3.1 ‘‘NAND Flash Mode’’ for more details).
So NAND Flash > 64MB can be supported on one chip select.

http://www.ti.com/lit/ug/sprugz3a/sprugz3a.pdf

硬件连接参考上面的文档3.1.1 Connecting to NAND Flash。