MPC555
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MPC556
QUEUED ANALOG-TO-DIGITAL CONVERTER MODULE-64
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
13-44
illustrates the operation of the queue structure.
Figure 13-12 QADC64 Conversion Queue Operation
To prepare the QADC64 for a scan sequence, the software writes to the CCW table to
specify the desired channel conversions. The software also establishes the criteria for
initiating the queue execution by programming the queue operating mode. The queue
operating mode determines what type of trigger event causes queue execution to be-
gin. “Trigger event” refers to any of the ways to cause the QADC64 to begin executing
the CCWs in a queue or sub-queue. An external trigger is only one of the possible trig-
ger events.
A scan sequence may be initiated by the following:
• A software command
QADC64 C
00
BEGIN Queue 1
BQ2
63
END OF Queue 1
BEGIN Queue 2
END OF Queue 2
P
IST
CHAN
6
8
7
9
11
12
13
14
10
15
P = PAUSE AFTER CONVERSION UNTIL NEXT TRIGGER
IST = INPUT SAMPLE TIME
CHAN = CHANNEL NUMBER AND END-OF-QUEUE CODE
10-BIT CONVERSION COMMAND
WORD FORMAT
00
63
RESULT
RESULT
S
RESULT
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
RIGHT JUSTIFIED, UNSIGNED RESULT
LEFT JUSTIFIED, UNSIGNED RESULT
LEFT JUSTIFIED, SIGNED RESULT
10-BIT RESULT, READABLE IN
THREE 16-BIT FORMATS
S = SIGN BIT
CHANNEL SELECT,
SAMPLE, HOLD, AND
A/D CONVERSION
CONVERSION COMMAND WORD
(CCW) TABLE
RESULT WORD TABLE
BYP
BYP = BYPASS BUFFER AMPLIFIER
6
8
7
11 12 13 14
10
15
5
4
3
2
1
9
0
LSB
MSB
LSB
MSB
6
8
7
11 12 13 14
10
15
5
4
3
2
1
9
0
LSB
MSB
6
8
7
11 12 13 14
10
15
5
4
3
2
1
9
0
LSB
MSB
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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