Event Processing and EDMA Control Registers
6-7
EDMA Controller
Once an event has been posted in the ER, the event can be cleared in two
ways. If the event is enabled in the event enable register (EER), the corre-
sponding event bit in the ER is cleared as soon as the EDMA submits a transfer
request for that event. Alternatively, if the event is disabled in the EER, the CPU
can clear the event by way of the event clear register (ECR), shown in
Figure 6–5. Writing a ‘1’ to any of the bits clears the corresponding event; writ-
ing a ’0’ has no effect. This feature allows the CPU to release a lock-up or error
condition. Therefore, once an event bit is set in the ER, it remains set until the
EDMA submits a transfer request for that event or the CPU clears the event
by setting the relevant bit in the ECR.
The CPU can also set events by way of the event set register (ESR) shown in
Figure 6–6. Writing a ‘1’ to one of the 16 event bits causes the corresponding
bit to be set in the event register. The event does not have to be enabled in this
case. This provides a good debugging tool and also allows the CPU to submit
EDMA requests in the system. Note that such CPU-initiated EDMA transfers
are basically unsynchronized transfers. In other words, an EDMA transfer oc-
curs when the relevant ER bit is set and is not triggered by any event as such.
Figure 6–3. Event Register (ER)
31
16
Reserved
R, +0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
EVT15
EVT14
EVT13
EVT12
EVT11
EVT10
EVT9
EVT8
EVT7
EVT6
EVT5
EVT4
EVT3
EVT2
EVT1
EVT0
R,+0
R,+0
R,+0
R,+0
R,+0
R,+0
R,+0
R,+0
R,+0
R,+0
R,+0
R,+0
R,+0
R,+0
R,+0
R,+0
Figure 6–4. Event Enable Register (EER)
31
16
Reserved
R, +0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
EE15
EE14
EE13
EE12
EE11
EE10
EE9
EE8
EE7
EE6
EE5
EE4
EE3
EE2
EE1
EE0
RW,+0
RW,+0
RW,+0
RW,+0
RW,+0
RW,+0
RW,+0
RW,+0
RW,+0
RW,+0
RW,+0
RW,+0
RW,+0
RW,+0
RW,+0
RW,+0