Motorola MPC533 Reference Manual page 466

Programming the QADC64E Registers
Table 13-9. QASR0 Bit Descriptions (continued)
Bits Name
4 TOR1
5 TOR2
13-22
PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE
Queue 1 Trigger Overrun — TOR1 indicates that an unexpected trigger event has occurred
for queue 1. TOR1 can be set only while queue 1 is in the active state.
A trigger event generated by a transition on the external trigger signal or by the
periodic/interval timer may be captured as a trigger overrun. TOR1 cannot occur when the
software initiated single-scan mode or the software initiated continuous-scan mode are
selected.
TOR1 occurs when a trigger event is received while a queue is executing and before the
scan has completed or paused. TOR1 has no effect on the queue execution.
After a trigger event has occurred for queue 1, and before the scan has completed or
paused, additional queue 1 trigger events are not retained. Such trigger events are
considered unexpected, and the QADC64E sets the TOR1 error status bit. An unexpected
trigger event may be a system overrun situation, indicating a system loading mismatch.
In external gated continuous-scan mode the definition of TOR1 has been redefined. In the
case when queue 1 reaches an end-of-queue condition for the second time during an open
gate, TOR1 becomes set. This is considered an overrun condition. In this case CF1 has
been set for the first end-of-queue 1 condition and then TOR1 becomes set for the second
end-of-queue 1 condition. For TOR1 to be set, software must not clear CF1 before the
second end-of-queue 1.
The software acknowledges that it has detected a trigger overrun being set by writing a zero
to the trigger overrun, after the bit was read as a one. Once set, only software or reset can
clear TOR1.
0 = No unexpected queue 1 trigger events have occurred
1 = At least one unexpected queue 1 trigger event has occurred (or queue 1 reaches an
end-of-queue condition for the second time in gated mode)
Queue 2 Trigger Overrun — TOR2 indicates that an unexpected trigger event has occurred
for queue 2. TOR2 can be set when queue 2 is in the active, suspended, and trigger
pending states.
The TOR2 trigger overrun can only occur when using an external trigger mode or a
periodic/interval timer mode. Trigger overruns cannot occur when the software initiated
single-scan mode and the software initiated continuous-scan mode are selected.
TOR2 occurs when a trigger event is received while queue 2 is executing, suspended, or a
trigger is pending. TOR2 has no effect on the queue execution. A trigger event that causes
a trigger overrun is not retained since it is considered unexpected.
An unexpected trigger event may be a system overrun situation, indicating a system
loading mismatch. The software acknowledges that it has detected a trigger overrun being
set by writing a zero to the trigger overrun, after the bit was read as a one. Once set, only
software or reset can clear TOR2.
0 = No unexpected queue 2 trigger events have occurred
1 = At least one unexpected queue 2 trigger event has occurred
MPC533 Reference Manual
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