MMC2107 - Freescale Semiconductor

Freescale Semiconductor, Inc.
Queued Analog-to-Digital Converter (QADC)
00
CONVERSION COMMAND
WORD (CCW) TABLE
RESULT WORD TABLE
BEGINNING OF QUEUE 1 00
•
•
•
END OF QUEUE 1
BEGINNING OF QUEUE 2
CHANNEL SELECT,
SAMPLE, HOLD,
A/D CONVERSION
•
•
•
nc...
Freescale Semiconductor, I
•
•
•
•
•
•
63 END OF QUEUE 2
63
10-BIT CONVERSION COMMAND
WORD FORMAT
9 8 [7:6] [5:0]
P BYP IST CHAN
P — PAUSE AFTER CONVERSION
UNTIL NEXT TRIGGER
BYP — BYPASS BUFFER AMPLIFIER
IST — INPUT SAMPLE TIME
CHAN — CHANNEL NUMBER AND
END-OF-QUEUE CODE
10-BIT RESULT, READABLE IN
THREE 16-BIT FORMATS
15 14 13 12 11 10
0 0 0 0 0 0 RESULT
Figure 18-44. QADC Conversion Queue Operation
To prepare the QADC 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 begin.
A trigger event refers to any of the ways to cause the QADC to begin
executing the CCWs in a queue or subqueue. An external trigger is only
one of the possible trigger events.
S
[9:0]
RIGHT-JUSTIFIED, UNSIGNED RESULT
[15:6]
RESULT 0 0 0 0 0 0
LEFT-JUSTIFIED, SIGNED RESULT
[15:6]
[5:0]
[5:0]
RESULT 0 0 0 0 0 0
LEFT-JUSTIFIED, UNSIGNED RESULT
A scan sequence may be initiated by:
• A software command
• Expiration of the periodic/interval timer
• External trigger signal
• External gated signal (queue 1 only)
Technical Data MMC2107 – Rev. 2.0
482 Queued Analog-to-Digital Converter (QADC) MOTOROLA
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