11DMA Ports
11 – 9
11.2.3 Byte Memory Word Formats
In your byte memory ROM or RAM, data is stored by the ADSP-21xx PROM
Splitter according to the data format you select: 24-bit program memory
words, 16-bit data memory words, 8-bit data memory bytes with MSB-
alignment, or 8-bit data memory bytes with LSB-alignment. The byte order
for 24-bit program memory words and 16-bit data memory words stored in
byte memory is most-significant-byte in the lower address. Table 11.1 shows
an example of byte memory storage of all four code/data formats.
Note: When transferring either of the data memory byte formats, the unused
byte of data memory is zero-filled.
Internal Internal Byte Memory Byte
Memory Memory Address Memory
BTYPE Address Contents (page 0x00) Contents
00 PM(0x0000) 0xABCDEF BM(0x0000) 0xAB
BM(0x0001) 0xCD
BM(0x0002) 0xEF
00 PM(0x0001) 0x123456 BM(0x0003) 0x12
BM(0x0004) 0x34
BM(0x0005) 0x56
01 DM(0x0000) 0x9876 BM(0x0006) 0x98
BM(0x0007) 0x76
01 DM(0x0001) 0x3456 BM(0x0008) 0x34
BM(0x0009) 0x56
10 DM(0x0002) 0x9800 BM(0x000A) 0x98
10 DM(0x0003) 0x7600 BM(0x000B) 0x76
11 DM(0x0004) 0x0034 BM(0x000C) 0x34
11 DM(0x0005) 0x0056 BM(0x000D) 0x56
Table 11.1 Byte Memory Storage Formats
11.2.4 BDMA Booting
The entire on-chip program memory of the ADSP-2181, or any portion of it,
can be loaded from an external source using a byte memory booting
sequence. Booting from byte memory is one of two methods available for
automatic booting after a reset.
Table 11.2 shows how to select the post-reset booting method using the
ADSP-2181’s MMAP and BMODE pins.
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