QADC64E Enhanced Mode Operation
MPC561/MPC563 Reference Manual, Rev. 1.2
Freescale Semiconductor
14-27
A queue is in the active state when a valid queue operating mode is selected, when the selected trigger
event has occurred, or when the QADC64E is performing a conversion specified by a CCW from that
queue.
Only one queue can be active at a time. Either or both queues can be in the paused state. A queue is paused
when the previous CCW executed from that queue had the pause bit set. The QADC64E does not execute
any CCWs from the paused queue until a trigger event occurs. Consequently, the QADC64E can service
queue 2 while queue 1 is paused.
Only queue 2 can be in the suspended state. When a trigger event occurs on queue 1 while queue 2 is
executing, the current queue 2 conversion is aborted. The queue 2 status is reported as suspended. Queue
2 transitions back to the active state when queue 1 becomes idle or paused.
A trigger pending state is required since both queues cannot be active at the same time. The status of queue
2 is changed to trigger pending when a trigger event occurs for queue 2 while queue 1 is active. In the
opposite case, when a trigger event occurs for queue 1 while queue 2 is active, queue 2 is aborted and the
status is reported as queue 1 active, queue 2 suspended. So due to the priority scheme, only queue 2 can
be in the trigger pending state.
There are two transition cases which cause the queue 2 status to be trigger pending before queue 2 is shown
to be in the active state. When queue 1 is active and there is a trigger pending on queue 2, after queue 1
completes or pauses, queue 2 continues to be in the trigger pending state for a few clock cycles. The
following are fleeting status conditions:
•
Queue 1 idle with queue 2 trigger pending
•
Queue 1 paused with queue 2 trigger pending
displays the status conditions of the queue status field as the QADC64E goes through the
transition from queue 1 active to queue 2 active.
Figure 14-13. Queue Status Transition
The queue status field is affected by the stop mode. Since all of the analog logic and control registers are
reset, the queue status field is reset to queue 1 idle, queue 2 idle.
Queue 1
Queue 2
Trigger Pending
Trigger Pending
Active
Idle
Active
Active
Idle (Paused)
Idle (Paused)
QADC64E QUEUE STATUS
Summary of Contents for MPC561
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Page 144: ...Signal Descriptions MPC561 MPC563 Reference Manual Rev 1 2 2 46 Freescale Semiconductor...
Page 206: ...Central Processing Unit MPC561 MPC563 Reference Manual Rev 1 2 3 62 Freescale Semiconductor...
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