MPC564EVB Freescale Semiconductor, MPC564EVB Datasheet - Page 509

• Manufacturer Part Number: MPC564EVB
• Description: KIT EVAL FOR MPC561/562/563/564
• Manufacturer: Freescale Semiconductor
• Type: Microcontrollerr

Specifications of MPC564EVB

• Contents: Module Board, Installation Guide, Power Supply, Cable, Software and more
• Processor To Be Evaluated: MPC56x
• Data Bus Width: 32 bit
• Interface Type: RS-232, Ethernet
• For Use With/related Products: MPC561, 562, 563, 564
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

When a queue is programmed for a continuous-scan mode, the single-scan enable bit in the queue control
register does not have any meaning or effect. As soon as the queue operating mode is programmed, the
selected trigger event can initiate queue execution.
In the case of the software-initiated continuous-scan mode, the trigger event is generated internally and
queue execution begins immediately. In the other continuous-scan queue operating modes, the selected
trigger event must occur before the queue can start. A trigger overrun is captured if a trigger event occurs
during queue execution in the external trigger continuous-scan mode and the periodic/interval timer
continuous-scan mode.
After the queue execution is complete, the queue status is shown as idle. Since the continuous-scan queue
operating modes allow the entire queue to be scanned multiple times, software involvement is not needed
to enable queue execution to continue from the idle state. The next trigger event causes queue execution
to begin again, starting with the first CCW in the queue.
In addition, the time from trigger to first conversion cannot be guaranteed since it is a function of clock
synchronization, programmable trigger events, queue priorities, and so on.
13.5.4.4.1
When the software initiated continuous-scan mode is programmed, the trigger event is generated
automatically by the QADC64E. Queue execution begins immediately. If a pause is encountered, another
trigger event is generated internally, and then execution continues without pausing. When the
end-of-queue is reached, another internal trigger event is generated, and queue execution begins again
from the beginning of the queue.
While the time to internally generate and act on a trigger event is very short, software can momentarily
read the status conditions, indicating that the queue is idle. The trigger overrun flag is never set while in
the software-initiated continuous-scan mode.
The software initiated continuous-scan mode keeps the result registers updated more frequently than any
of the other queue operating modes. The software can always read the result table to get the latest
converted value for each channel. The channels scanned are kept up to date by the QADC64E without
software involvement. Software can read a result value at any time.
The software initiated continuous-scan mode may be chosen for either queue, but is normally used only
with queue 2. When the software initiated continuous-scan mode is chosen for queue 1, that queue operates
Freescale Semiconductor
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External trigger continuous-scan mode
External gated continuous-scan mode
Periodic/interval timer continuous-scan mode
Coherent samples are guaranteed. The time between consecutive
conversions has been designed to be consistent. However, there is one
exception. For queues that end with a CCW containing EOQ code (channel
63), the last queue conversion to the first queue conversion requires 1
additional CCW fetch cycle. Therefore continuous samples are not coherent
at this boundary.
Software Initiated Continuous-Scan Mode
MPC561/MPC563 Reference Manual, Rev. 1.2
NOTE
QADC64E Legacy Mode Operation
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