在“KeyStone Architecture External Memory Interface (EMIF16) User Guide”中,提到“EMIFA[23:22] behave as address selects”,是不是EMIFA[23:22] 相当于BA[1:0]?
16位宽时,A23接FLASH的A0,那A22呢?A22还是当地址位吗?这时EMIF16还是支持32MB吗?
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在“KeyStone Architecture External Memory Interface (EMIF16) User Guide”中,提到“EMIFA[23:22] behave as address selects”,是不是EMIFA[23:22] 相当于BA[1:0]?
16位宽时,A23接FLASH的A0,那A22呢?A22还是当地址位吗?这时EMIF16还是支持32MB吗?
(1)从User Guide上看,EMIF是支持32MB NORFlash的: “A total of 256M bytes of any of these memories can be accessed at any given time via four chip selects with 64M byte access per chip select.”
(2)是不是EMIFA[23:22] 相当于BA[1:0]?
在16bit接口时,EMIFA的[22:0]连到Flash的A[N:0],EMIFA[23]是“connected to address pin A0 of the ASRAM/NOR Flash”作为“address selects”。
在8bit接口时,EMIFA的[21:0]连到Flash的A[N:0],EMIFA[23:22] connected to address pins A[1:0]。
(3)16位宽时,A23接FLASH的A0,A22还是当地址位吗?这时EMIF16还是支持32MB吗?
A22此时还是作地址位,这时EMIF16还是支持32MB的。我的理解是,EMIFA[23:0]这24位虽然在Flash这一侧功能有不同,但是从EIMIF上看,这24位都是外部地址接口,每个CE所支持的Flash容量为2^24*16bit=2^28bit=32M byte.
如果6678外接16位nor flash,是不是EMIFA23和EMIFA0都接到NOR FLASH的最低位了呢?
是不是 “在16bit接口时,EMIFA的[22:0]连到Flash的A[N:0],EMIFA[23]是“connected to address pin A0 of the ASRAM/NOR Flash”作为“address selects”。
在8bit接口时,EMIFA的[21:0]连到Flash的A[N:0],EMIFA[23:22] connected to address pins A[1:0]。”
改成
“在16bit接口时,EMIFA的[22:0]连到Flash的A[N:1],EMIFA[23]是“connected to address pin A0 of the ASRAM/NOR Flash”作为“address selects”。
在8bit接口时,EMIFA的[21:0]连到Flash的A[N:2],EMIFA[23:22] connected to address pins A[1:0]。”
这样比较好呢?