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DM355 Boot modes
The ROM bootloader only supports NAND/MMC-SD/UART; However DM355 also supports direct AEMIF Boot for OneNAND using BTSEL[0:1] =10 option. The DM355 EVM does not support the AEMIF-NOR boot mode as it does not have any NOR memory on board. There is nothing preventing the user for using a NOR flash instead of the OneNAND, however there is a big limitation of only 16 AEMIF address lines available which will limit the NOR to an 8bit 64Kbyte/Chip select or 16bit 128kbyte/chip select (at EMIF half rate). This is one of the primary reasons we don’t specifically spell out support for NOR boot via the AEMIF direct boot.
The AECFG[3:0] pins configuration that they will have to select if they attach a NOR instead of a OneNAND, for 8bit=AECFG=1000, and for 16bit=AECFG=0010.
Also note that for AEMIF boot, the OneNAND must be connected to the first AEMIF chip select space (EM_CE0). Also, the AEMIF does not support direct execution from NAND Flash.