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Digital Control Subsystem
Conversion Command
Word (CCW) Table
00
Beginning of Queue 1
End of Queue 1
Beginning of Queue 2
63
End of Queue 2
10-bit Conversion Command
9
P
BYP
P — Pause after Conversion
until Next Trigger
BYP — Bypass Buffer Amplifier
IST — Input Sample Time
CHAN — Channel Number and
Figure 27-43. QADC Conversion Queue Operation
To prepare the QADC for a scan sequence, write to the CCW table to specify the desired
channel conversions. The criteria for queue execution is established by selecting the queue
operating mode. The queue operating mode determines what type of trigger event starts
queue execution. A trigger event refers to any of the ways that cause the QADC to begin
executing the CCWs in a queue or subqueue. An external trigger is only one of the possible
trigger events.
A scan sequence may be initiated by:
• A software command
• Expiration of the periodic/interval timer
• An external trigger signal
• An external gated signal (queue 1 only)
The queue can be scanned in single pass or continuous fashion. When a single-scan mode
is selected, the scan must be engaged by setting the single-scan enable bit. When a
continuous-scan mode is selected, the queue remains active in the selected queue operating
mode after the QADC completes each queue scan sequence.
27-60
•
•
•
Channel Select,
Sample, Hold,
A/D Conversion
•
•
•
Word Format
8
[7:6]
[5:0]
IST
CHAN
End-of-Queue Code
MCF5282 User's Manual
Result Word Table
•
•
•
•
•
•
10-bit Result, Readable in
Three 16-BIT Formats
15 14 13 12 11 10
[9:0]
0
0 0 0 0 0
RESULT
Right-Justified, Unsigned Result
[15:6]
[5:0]
S
RESULT
0
0 0 0 0 0
Left-Justified, Signed Result
[15:6]
[5:0]
RESULT
0
0 0 0 0 0
Left-Justified, Unsigned Result
00
63
MOTOROLA
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