Texas Instruments TMS320C54x, User Manual

Page: 314 / 469

Understanding Memory Widths
10-14
10.4.5 A Memory Configuration Example
Figure 10–5 shows a typical memory configuration example. This memory
system consists of two 128K
8-bit ROM devices.
Figure 10–5. ’C54x Memory Configuration Example
Upper 8 bits (data)
Lower 8 bits (data)
System memory width 16 bits
ROM width
8 bits 8 bits
ROM width
ROM1
128K x 8
ROM0
128K x 8
CPU
Source file
word AABBh
AABBh
AAh BBh
Data width = 16 bits
10.4.6 Specifying Word Order for Output Words
When memory words are narrower than target words (memory width < 16), tar-
get words are split into multiple consecutive memory words. There are two
ways to split a wide word into consecutive memory locations in the same hex
conversion utility output file:
-
–order MS specifies big-endian ordering, in which the most significant
part of the wide word occupies the first of the consecutive locations
-
–order LS specifies little-endian ordering, in which the the least signifi-
cant part of the wide word occupies the first of the consecutive locations
By default, the utility uses little-endian format because the ’C54x boot loaders
expect the data in this order. Unless you are using your own boot loader pro-
gram, avoid using –order MS.