Motorola PowerQUICC II MPC8280 Series Reference Manual page 694

IDMA Operation
IDMAx BD Base
Address (IBASE)
Source Device or
Buffer 0
Source Device or
Buffer 1
Source Device or
Buffer 2
• •
•
Source Device or
Buffer n
Data associated with each IDMA channel is stored in buffers and each buffer is referenced
by a BD that uses a circular table structure in the dual-port RAM. Control options such as
interrupt and DONE assertion are also programmed on a per-buffer basis in each BD.
Data may be transferred in the two following modes:
• Auto buffer mode. The IDMA continuously transfers data to/from the location
programmed in the BD until a
externally.
• Buffer chaining mode. Data is transferred according to the first BD parameters, then
the second BD and so forth. The first BD is reused (if ready) until the BD with the
last bit set is reached. IDMA transfers stop and restarts when the BD table is
reinitialized and a
19.8.2 IDMAx Parameter RAM
When an IDMAx channel is configured to auto buffer or buffer chaining mode, the
MPC8280 uses the IDMAx parameters listed in the Table 19-4. Parameters should be
modified only while the channel is disabled, that is, before the first
or when the event register's stop-completed bit (IDSR[SC]) is set following a
command.
Each IDMAx channel parameter table can be placed at any 64-byte aligned address in the
dual-port RAM's general-purpose area (banks 1–8, 11 and 12). The CP accesses each
19-18
Freescale Semiconductor, Inc.
BD 0
BD 1
BD 2
•
•
•
BD n
Figure 19-7. IDMAx Channel BD Table
_
STOP
_ command is issued.
START IDMA
MPC8280 PowerQUICC II Family Reference Manual
For More Information On This Product,
Go to: www.freescale.com
Destination Device or
Destination Device or
Destination Device or
Destination Device or
command is issued or DONE is asserted
IDMA
Buffer 0
Buffer 1
Buffer 2
• •
•
Buffer n
_ command
START IDMA
_
STOP IDMA
MOTOROLA