MMC2107 Datasheet, PDF (456/618 Pages) –

Freescale Semiconductor, Inc.
Queued Analog-to-Digital Converter (QADC)
In situation S2 (Figure 18-24), more than one trigger event is recognized
before servicing of a previous trigger event is complete, the trigger
overrun bit is again set, but otherwise, the additional trigger events are
ignored. After the queue is complete, the first newly detected trigger
event causes queue execution to begin again. When the trigger event
rate is high, a new trigger event can be seen very soon after completion
of the previous queue, leaving software little time to retrieve the previous
results. Also, when trigger events are occurring at a high rate for
queue 1, the lower priority queue 2 channels may not get serviced at all.
T1 T1 T1 T1
Q1: C1 C2 C3 C4
T1
C1 C2 C3 C4
TOR1 TOR1 TOR1 CF1
CF1
Q1 IDLE
ACTIVE
IDLE
ACTIVE
T2
T2 T2
Q2: C1 C2 C3 C4
TOR2 TOR2
CF2
IDLE
Q2
IDLE
ACTIVE
IDLE
QS
1000
1000
0000
0010
0000
Figure 18-24. CCW Priority Situation 2
Technical Data
456
Queued Analog-to-Digital Converter (QADC)
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MMC2107 – Rev. 2.0
MOTOROLA