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Registers
671
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Enhanced Direct Memory Access (EDMA3) Controller
17.4.2.5.3
Event Set Register (ESR)
The event set register (ESR) allows the CPU (or EDMA programmers) to manually set events to initiate
DMA transfer requests. CPU writes of 1 to any event set register (E
n
) bits set the corresponding bits in the
registers. The set event is evaluated by the EDMA3CC logic for an associated transfer request submission
to the transfer controllers. Writing a 0 has no effect.
The event set register operates independent of the event register (ER), and a write of 1 is always
considered a valid event regardless of whether the event is enabled (the corresponding event bits are set
or cleared in EER.E
n
).
Once the event is set in the event set register, it cannot be cleared by CPU writes, in other words, the
event clear register (ECR) has no effect on the state of ESR. The bits will only be cleared once the
transfer request corresponding to the event has been submitted to the transfer controller. The setting of an
event is a higher priority relative to clear operations (via hardware). If set and clear conditions occur
concurrently, the set condition wins. If the event was previously set, then EMR would be set since an
event is lost. If the event was previously clear, then the event remains set and is prioritized for submission
to the event queues.
Manually-triggered transfers via writes to ESR allow the CPU to submit DMA requests in the system,
these are relevant for memory-to-memory transfer scenarios. If the ESR.E
n
bit is already set and another
CPU write of 1 is attempted to the same bit, then the corresponding event is latched in the event missed
registers (EMR.E
n
= 1).
The ESR is shown in
and described in
.
Figure 17-63. Event Set Register (ESR)
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
E31
E30
E29
E28
E27
E26
E25
E24
E23
E22
E21
E20
E19
E18
E17
E16
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
E15
E14
E13
E12
E11
E10
E9
E8
E7
E6
E5
E4
E3
E2
E1
E0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
LEGEND: R/W = Read/Write; -
n
= value after reset
Table 17-45. Event Set Register (ESR) Field Descriptions
Bit
Field
Value
Description
31-0
E
n
Event set for event 0-31.
0
No effect.
1
Corresponding DMA event is prioritized versus other pending DMA/QDMA events for submission to the
EDMA3TC.