Channel 32, array 0
Intermediate
transfer complete
(A)
Channel 63, array 0
Event 32
Hardwired event
(tied to GPINT0, event 32)
Chained event
(event 63)
Channel 32, array 1
Event 32
Channel 63, array 1
Intermediate
transfer complete
(A)
Channel 63, array 3
Channel 32, array 3
Channel 32, array 2
Event 32
Event 32
Channel 63, array 2
Transfer complete
(B)
Intermediate
transfer complete
(A)
(last array)
Transfer complete sets
IPRH.I63 = 1
If IPRH.I63 = 1,
EDMACC_INT* sent
Notes:
(A) Intermediate transfer complete chaining synchronizes event 63
ITCCHEN = 1, TCC = 011 1111b and sets CERH.E63 = 1
(B) Transfer complete chaining synchronizes event 63
TCCHEN = 1, TCC = 011 1111b and sets CERH.E63 = 1
to CPU
Enable transfer
complete chaining:
OPT.TCCHEN = 1
OPT.TCC = 011 1111b
Enable intermediate transfer
complete chaining:
OPT.ITCCHEN = 1
OPT.TCC = 011 1111b
Disable intermediate transfer
OPT.TCINTEN = 1
OPT.ITCCHEN = 0
complete chaining:
OPT.TCC = 011 1111b
completion interrupt:
Enable transfer
Setup
Channel 32 parameters
for chaining
for chaining
Channel 63 parameters
Enable channel 32
EERH.E32 = 1
Event enable register (EER)
3.4.5.2
Breaking Up Large Transfers with Intermediate Chaining
www.ti.com
Peripheral Servicing Example
Figure 3-18. Intermediate Transfer Completion Chaining Example
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.
SPRUG34 – November 2008
EDMA3 Transfer Examples
83
Содержание TMS320DM357
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