Motorola MPC533 Reference Manual page 566

Digital Subsystem
Multiple end-of-queue conditions may be recognized
simultaneously, although there is no change in the QADC64E
behavior. For example, if BQ2 is set to CCW0, CCW0 contains
the EOQ code, and a trigger event occurs on queue 1, the
QADC64E reads CCW0 and detects both end-of-queue
conditions. The completion flag is set and queue 1 becomes
idle.
Boundary conditions also exist for combinations of pause and end-of-queue. One case is
when a pause bit is in one CCW and an end-of-queue condition is in the next CCW. The
conversion specified by the CCW with the pause bit set completes normally. The pause flag
is set. However, since the end-of-queue condition is recognized, the completion flag is also
set and the queue status becomes idle, not paused. Examples of this situation include:
• The pause bit is set in CCW5 and the EOQ code is in CCW6
• The pause is set in CCW63
• During queue 1 operation, the pause bit is set in CCW20 and BQ2 points to CCW21
Another pause and end-of-queue boundary condition occurs when the pause and an
end-of-queue condition occur in the same CCW. Both the pause and end-of-queue
conditions are recognized simultaneously. The end-of-queue condition has precedence so a
conversion is not performed for the CCW and the pause flag is not set. The QADC64E sets
the completion flag and the queue status becomes idle. Examples of this situation are:
• The pause bit is set in CCW10 and EOQ is programmed into CCW10
• During queue 1 operation, the pause bit set in CCW32, which is also BQ2
14.5.4 Scan Modes
The QADC64E queuing mechanism allows the application to utilize different requirements
for automatically scanning input channels.
In single-scan mode, a single pass through a sequence of conversions defined by a queue is
performed. In continuous-scan mode, multiple passes through a sequence of conversions
defined by a queue are executed. The possible modes are:
• Disabled and reserved mode
• Single-scan modes
— Software initiated single-scan mode
— External trigger single-scan mode
— External gated single-scan mode
— Periodic/Interval timer single-scan mode
• Continuous-scan modes
14-42
PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE
NOTE
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