Chaining EDMA3 Channels
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Chaining is different from linking (
). The EDMA3 link feature reloads the current channel
parameter set with the linked parameter set. The EDMA3 chaining feature does not modify or update any
channel parameter set; it provides a synchronization event to the chained channel (see
for
chain-triggered transfer requests).
Chaining is achieved at either final transfer completion or intermediate transfer completion, or both, of the
current channel. Consider a channel
m
(DMA/QDMA) required to chain to channel
n
. Channel number
n
(0-63) needs to be programmed into the TCC field of channel
m
channel options parameter (OPT) set.
•
If final transfer completion chaining (TCCHEN = 1 and ITCCHEN = 0 in channel
m
OPT) is enabled,
the chain-triggered event occurs after the
last
transfer request of channel
m
is submitted (early
completion) or completed (normal completion).
•
If intermediate transfer completion chaining (ITCCHEN = 1 and ITCCHEN = 0 in channel
m
OPT) is
enabled, the chain-triggered event occurs after every
intermediate
transfer request of channel
m
is
submitted (early completion) or completed (normal completion).
•
If both final and intermediate transfer completion chaining (TCCHEN = 1 and ITCCHEN = 1 in channel
m
OPT) are enabled, the chain-trigger event occurs after
every
transfer request of channel
m
is
submitted (early completion) or completed (normal completion).
shows the number of chain event triggers occurring in different synchronized scenarios.
Consider channel 31 programmed with ACNT = 3, BCNT = 4, CCNT = 5, and TCC = 30.
Table 2-10. Chain Event Triggers
(Number of chained event triggers on channel 30)
Options
A-Synchronized
AB-Synchronized
TCCHEN = 1, ITCCHEN = 0
1 (Last TR)
1 (Last TR)
TCCHEN = 0, ITCCHEN = 1
19 (All but the last TR)
4 (All but the last TR)
TCCHEN = 1, ITCCHEN = 1
20 (All TRs)
5 (All TRs)
EDMA3 Architecture
48
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