Event
register
(ER/ERH)
Event
enable
register
(EER/EERH)
Event
set
register
(ESR/ESRH)
Chained
event
register
(CER/CERH)
QDMA
event
register
(QER)
64
64
64
64:1 priority encoder
8:1 priority encoder
8
Event queues
Channel mapping
Queue bypass
Parameter
set 0
Parameter
set 1
set 255
Parameter
Parameter
set 254
T
ransfer request process submit
PaRAM
E63
E0
E1
To
TC(S)
From
EDMA3TC0
From
EDMA3TC3
Completion
interface
Completion
detection
Event
trigger
Manual
trigger
Chain
trigger
Completion
interrupt
detection
Error
EDMA3CC_INT[7:0]
From peripherals/external events
EDMA3CC_ERRINT
QDMA trigger
Memory
protection
Read/
write to/
from CPU
EDMA3CC_
MPINT
To chained event register (CER/CERH)
0
15
EDMA3
channel
controller
Early completion
Queue 0
0
15
Queue 1
0
15
Queue 2
0
15
Queue 3
Functional Description
Figure 11-4. EDMA3 Channel Controller (EDMA3CC) Block Diagram
A trigger event is needed to initiate a transfer. A trigger event may be due to an external event, manual
write to the event set register, or chained event for DMA channels. QDMA channels auto-trigger when a
write to the trigger word that you program occurs on the associated PaRAM set. All such trigger events
are logged into appropriate registers upon recognition.
Once a trigger event is recognized, the appropriate event gets queued in the EDMA3CC event queue. The
assignment of each DMA/QDMA channel to an event queue is programmable. Each queue is 16 events
deep; therefore, you can queue up to 16 events (on a single queue) in the EDMA3CC at a time. Additional
pending events that are mapped to a full queue are queued when the event queue space becomes
available. See
If events on different channels are detected simultaneously, the events are queued based on a fixed
priority arbitration scheme with the DMA channels being higher priority events than the QDMA channels.
Among the two groups of channels, the lowest-numbered channel is the highest priority.
877
SPRUH73H – October 2011 – Revised April 2013
Enhanced Direct Memory Access (EDMA)
Copyright © 2011–2013, Texas Instruments Incorporated