Introduction
580
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Enhanced Direct Memory Access (EDMA3) Controller
Term
Meaning
EDMA3 channel
controller
(EDMA3CC)
The user-programmable portion of the EDMA3. The EDMA3CC contains the
parameter RAM (PaRAM) , event processing logic, DMA/QDMA channels, event
queues, etc. The EDMA3CC services events (external, manual, chained, QDMA)
and is responsible for submitting transfer requests to the transfer controllers
(EDMA3TC), which perform the actual transfer.
EDMA3
programmer
Any entity on the chip that has read/write access to the EDMA3 registers and can
program an EDMA3 transfer.
EDMA3 transfer
controller(s)
(EDMA3TC)
Transfer controllers are the transfer engine for the EDMA3. Performs the
read/writes as dictated by the transfer requests submitted by the EDMA3CC.
Enhanced direct
memory access
(EDMA3)
controller
Consists of the EDMA3 channel controller (EDMA3CC) and EDMA3 transfer
controller(s) (EDMA3TC). Is referred to as EDMA3 in this document.
Link parameter set
A PaRAM set that is used for linking.
Linking
The mechanism of reloading a PaRAM set with new transfer characteristics on
completion of the current transfer.
Memory-mapped
slave
All on-chip memories, off-chip memories, and slave peripherals. These typically rely
on the EDMA3 (or other master peripheral) to perform transfers to and from them.
Master
peripherals
All peripherals that are capable of initiating read and write transfers to the
peripherals system and may not solely rely on the EDMA3 for their data transfers.
Null set or Null
PaRAM set
A PaRAM set that has all count fields cleared (except for the link field). A dummy
PaRAM set has at least one of the count fields nonzero.
Null transfer
A trigger event for a null PaRAM set results in the EDMA3CC performing a null
transfer. This is an error condition. A dummy transfer is not an error condition.
QDMA channel
One of the 8 channels that can be triggered when writing to the trigger word
(TRWORD) of a PaRAM set. All QDMA channels exist in the EDMA3CC.
Parameter RAM
(PaRAM)
Programmable RAM that stores PaRAM sets used by DMA channels, QDMA
channels, and linking.
Parameter RAM
(PaRAM) set
A 32-byte EDMA3 channel transfer definition. Each parameter set consists of
8 words (4-bytes each), which store the context for a DMA/QDMA/link transfer. A
PaRAM set includes source address, destination address, counts, indexes, options,
etc.
Parameter RAM
(PaRAM) set entry
One of the 4-byte components of the parameter set.
Slave end points
All on-chip memories, off-chip memories, and slave peripherals. These rely on the
EDMA3 to perform transfers to and from them.
Transfer request
(TR)
A command for data movement that is issued from the EDMA3CC to the
EDMA3TC. A TR includes source and destination addresses, counts, indexes,
options, etc.
Trigger event
Action that causes the EDMA3CC to service the PaRAM set and submit a transfer
request to the EDMA3TC. Trigger events for DMA channels include manual
triggered (CPU triggered), external event triggered, and chain triggered. Trigger
events for QDMA channels include autotriggered and link triggered.
Trigger word
For QDMA channels, the trigger word specifies the PaRAM set entry that when
written results in a QDMA trigger event. The trigger word is programmed via the
QDMA channel
n
mapping register (QCHMAP
n
) and can point to any PaRAM set
entry.
TR synchronization
(sync) event
See Trigger event.