SPRS377F September 2008 – June 2014 TMS320C6745 , TMS320C6747
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Figure 6-12 illustrates an example of how SDRAM, NOR, and NAND flash devices might be connected to EMIFA of a C6745/6747 device simultaneously. The SDRAM chip select must be EMA_CS[0]. Note that the NOR flash is connected to EMA_CS[2] and the NAND flash is connected to EMA_CS[3] in this example. Note that any type of asynchronous memory may be connected to EMA_CS[5:2].
The on-chip bootloader makes some assumptions on which chip select the contains the boot image, and this depends on the boot mode. For NOR boot mode; the on-chip bootloader requires that the image be stored in NOR flash on EMA_CS[2]. For NAND boot mode, the bootloader requires that the boot image is stored in NAND flash on EMA_CS[3]. It is always possible to have the image span multiple chip selects, but this must be supported by second stage boot code stored in the external flash.
A likely use case with more than one EMIFA chip select used for NAND flash is illustrated in Figure 6-13. This figure shows how two multiplane NAND flash devices with two chip selects each would connect to the EMIFA. In this case if NAND is the boot memory, then the boot image needs to be stored in the NAND area selected by EMA_CS[3]. Part of the application image could spill over into the NAND regions selected by other EMIFA chip selects; but would rely on the code stored in the EMA_CS[3] area to bootload it. Note that this example could also apply to the C6745 device; except only one multiplane NAND could be supported with only EMA_CS[3:2] available.