Architecture
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SPRUH91D–March 2013–Revised September 2016
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Enhanced Direct Memory Access (EDMA3) Controller
After the TR is read from the PaRAM (and is in process of being submitted to EDMA3TC), the following
fields are updated if needed:
• A-synchronized: BCNT, CCNT, SRC, DST
• AB-synchronized: CCNT, SRC, DST
The following fields are not updated (except for during linking, where all fields are overwritten by the link
PaRAM set):
• A-synchronized: ACNT, BCNTRLD, SRCBIDX, DSTBIDX, SRCCIDX, DSTCIDX, OPT, LINK
• AB-synchronized: ACNT, BCNT, BCNTRLD, SRCBIDX, DSTBIDX, SRCCIDX, DSTCIDX, OPT, LINK
Note that PaRAM updates only pertain to the information that is needed to properly submit the next
transfer request to the EDMA3TC. Updates that occur while data is moved within a transfer request are
tracked within the transfer controller, and is detailed in Section 16.2.11. For A-synchronized transfers, the
EDMA3CC always submits a TRP for ACNT bytes (BCNT = 1 and CCNT = 1). For AB-synchronized
transfers, the EDMA3CC always submits a TRP for ACNT bytes of BCNT arrays (CCNT = 1). The
EDMA3TC is responsible for updating source and destination addresses within the array based on ACNT
and FWID (in OPT). For AB-synchronized transfers, the EDMA3TC is also responsible to update source
and destination addresses between arrays based on SRCBIDX and DSTBIDX.
Table 16-3 shows the details of parameter updates that occur within EDMA3CC for A-synchronized and
AB-synchronized transfers.
(1)
In all cases, no updates occur if OPT.STATIC == 1 for the current PaRAM set.
Table 16-3. Parameter Updates in EDMA3CC (for Non-Null, Non-Dummy PaRAM Set)
A-Synchronized Transfer AB-Synchronized Transfer
B-Update C-Update Link Update B-Update C-Update Link Update
Condition: BCNT > 1
BCNT == 1 &&
CCNT > 1
BCNT == 1 &&
CCNT == 1 N/A CCNT > 1 CCNT == 1
SRC += SRCBIDX += SRCCIDX = Link.SRC in EDMA3TC += SRCCIDX = Link.SRC
DST += DSTBIDX += DSTCIDX = Link.DST in EDMA3TC += DSTCIDX = Link.DST
ACNT None None = Link.ACNT None None = Link.ACNT
BCNT –= 1 = BCNTRLD = Link.BCNT in EDMA3TC N/A = Link.BCNT
CCNT None –= 1 = Link.CCNT in EDMA3TC –=1 = Link.CCNT
SRCBIDX None None = Link.SRCBIDX in EDMA3TC None = Link.SRCBIDX
DSTBIDX None None = Link.DSTBIDX None None = Link.DSTBIDX
SRCCIDX None None = Link.SRCBIDX in EDMA3TC None = Link.SRCBIDX
DSTCIDX None None = Link.DSTBIDX None None = Link.DSTBIDX
LINK None None = Link.LINK None None = Link.LINK
BCNTRLD None None = Link.BCNTRLD None None = Link.BCNTRLD
OPT
(1)
None None = LINK.OPT None None = LINK.OPT
NOTE: The EDMA3CC includes no special hardware to detect when an indexed address update
calculation overflows/underflows. The address update will wrap across boundaries as
programmed by the user. You should ensure that no transfer is allowed to cross internal port
boundaries between peripherals. A single TR must target a single source/destination slave
endpoint.
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