MMC2114 MOTOROLA [Motorola, Inc], MMC2114 Datasheet - Page 504

• Manufacturer Part Number: MMC2114
• Description: M CORE Microcontrollers
• Manufacturer: MOTOROLA [Motorola, Inc]

Queued Analog-to-Digital Converter (QADC)
19.10.9 Periodic/Interval Timer
Advance Information
504
CAUTION:
NOTE:
A change in the prescaler value while a conversion is in progress is likely
to corrupt the result. Therefore, any prescaler write operation should be
done only when both queues are in the disabled modes.
To accommodate the wide range of the main MCU clock frequency,
QCLK is generated by a programmable prescaler which divides the
MCU system clock. To allow the A/D conversion time to be maximized
across the spectrum of system clock frequencies, the QADC prescaler
permits the QCLK frequency to be software selectable. The frequency of
QCLK is set with the QPR field in QACR0.
The MCU system clock frequency is the basis of QADC timing. The
QADC requires that the system clock frequency be at least twice the
QCLK frequency.
The QADC periodic/interval timer can be used to generate trigger events
at a programmable interval, initiating execution of queue 1 and/or
queue 2. The periodic/interval timer stays reset under these conditions:
Interval timer single-scan mode does not start the periodic/interval timer
until the single-scan enable bit is set.
These conditions will cause a pulsed reset of the periodic/interval timer
during use:
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Freescale Semiconductor, Inc.
For More Information On This Product,
Queued Analog-to-Digital Converter (QADC)
Both queue 1 and queue 2 are programmed to any mode which
does not use the periodic/interval timer.
System reset is asserted.
Stop mode is enabled.
Debug mode is enabled.
A queue 1 operating mode change to a mode which uses the
periodic/interval timer, even if queue 2 is already using the timer
A queue 2 operating mode change to a mode which uses the
periodic/interval timer, provided queue 1 is not in a mode which
uses the periodic/interval timer
Roll over of the timer
Go to: www.freescale.com
MMC2114 • MMC2113 • MMC2112 — Rev. 1.0
MOTOROLA