Expansion Bus I/O Port Operation
8-20
8.4.3
DMA Transfer Examples
8.4.3.1
Example 1 (single frame transfer)
Peripherals located on the I/O port of the expansion bus are accessible only
via DMA transactions. This section gives a very simple example used to trans-
fer a single frame of 256 words from a FIFO located in XCE0 into internal data
memory at 8000 0000h. This example simply sets up the source and destina-
tion registers, and starts the DMA with incrementing destination address and
a non-changing source address. The source address does not change, since
the FIFO is located in a fixed memory location. The content of relevant regis-
ters and DMA channel primary control register are shown in Table 8–9 and
Table 8–10.
Table 8–9. Content of Relevant Registers (single frame transfer)
Register
Contents
DMA primary control register
0000 0041h
DMA source
4000 0000h
DMA destination
8000 0000h
Transfer counter register
0000 0100h
Table 8–10. Content of DMA Channel Primary Control Register Fields
DST
reload
SRC
reload
EMOD
FS
TCINT
PRI
WSYNC
RSYNC
INDEX
CNT
reload
SPLIT
ESZISE
DST
DIR
SRC
DIR
STATUS
START
00
00
0
0
0
0
00000 00000 0
0
00
00
01
00
00
01