11 DMA Ports
11 – 26
• SPORT Autobuffering to External Memory with Waitstated Access –
When one of the processor’s serial ports needs to access external
memory for autobuffering and the external access takes more than one
cycle, the IDMA transfer will be held off.
• EZ-ICE Emulation – When the EZ-ICE emulator is controlling your
ADSP-2181 target system, IDMA transfers may be held off for periods
of time.
Using the
IACK
signal simplifies your system design by allowing you to
ignore hold-off conditions. If you always wait for
IACK
to assert before
accessing the IDMA port, the DMA transfers will always operate properly.
You can ignore
IACK
, however, if you are sure that no hold-offs occur in your
system or if your IDMA accesses are longer than any hold-offs. To be sure of
this, you must carefully analyze all possible hold-off conditions of your
system.