Channel 48, array 0
Intermediate
transfer complete
(A)
Channel 8, array 0
Event 48
Hardwired event
(tied to GPINT0, event 48)
Chained event
(event 8)
Channel 48, array 1
Event 48
Channel 8, array 1
Intermediate
transfer complete
(A)
Channel 8, array 3
Channel 48, array 3
Channel 48, array 2
Event 48
Event 48
Channel 8, array 2
Transfer complete
(B)
Intermediate
transfer complete
(A)
(last array)
Transfer complete sets
IPR.I8 = 1
If IPR.I8 = 1, interrupt
EDMACC_INT* sent
Notes:
(A) Intermediate transfer complete chaining synchronizes event 8
ITCCHEN = 1, TCC = 01000b, and sets CER.E8 = 1
(B) Transfer complete chaining synchronizes event 8
TCCHEN =1, TCC = 01000b and sets CER.E8 = 1
to CPU
Enable transfer
complete chaining:
OPT.TCCHEN = 1
OPT.TCC = 01000b
Enable intermediate transfer
complete chaining:
OPT.ITCCHEN = 1
OPT.TCC = 01000b
Disable intermediate transfer
OPT.TCINTEN = 1
OPT.ITCCHEN = 0
complete chaining:
OPT.TCC = 01000b
complete chaining:
Enable transfer
Setup
Channel 48 parameters
for chaining
for chaining
Channel 8 parameters
Enable channel 48
EER.E48 = 1
Event enable register (EER)
Functional Description
Figure 11-39. Intermediate Transfer Completion Chaining Example
11.3.19.4.5.2 Breaking Up Large Transfers with Intermediate Chaining
Another feature of intermediate transfer chaining (ITCCHEN) is for breaking up large transfers. A large
transfer may lock out other transfers of the same priority level for the duration of the transfer. For example,
a large transfer on queue 0 from the internal memory to the external memory using the EMIF may starve
other EDMA3 transfers on the same queue. In addition, this large high-priority transfer may prevent the
EMIF for a long duration to service other lower priority transfers. When a large transfer is considered to be
high priority, it should be split into multiple smaller transfers.
shows the EDMA3 setup and
illustration of an example single large block transfer.
934
Enhanced Direct Memory Access (EDMA)
SPRUH73H – October 2011 – Revised April 2013
Copyright © 2011–2013, Texas Instruments Incorporated