XC886/888CLM
Analog-to-Digital Converter
User’s Manual
16-16
V1.3, 2010-02
ADC, V 1.0
16.4.5.3
External Trigger
The conversion request for the parallel source (and also the sequential source) can be
synchronized to an external trigger event. For the parallel source, this is done by
coupling the reload event to a request trigger input, REQTR.
16.4.5.4
Software Control
The load event for the parallel source can also be generated under software control in
two ways:
•
The conversion request control register can be written at two different addresses
(CRCR1 and CRPR1). Accessed at CRCR1, the write action changes only the bits in
this register. Accessed at CRPR1, a load event will take place one clock cycle after
the write access. This automatic load event can be used to start conversions with a
single move operation. In this case, the information about the channels to be
converted is given as an argument in the move instruction.
•
Bit LDEV can be written with 1 by software to trigger the load event. In this case, the
load event does not contain any information about the channels to be converted, but
always takes the contents of the conversion request control register. This allows the
conversion request control register to be written at a second address without
triggering the load event.
16.4.5.5
Autoscan
The autoscan is a functionality of the parallel source. If autoscan mode is enabled, the
load event takes place when the conversion is completed while PND = 0, provided the
parallel request source has triggered the conversion. This automatic reload feature
allows channels 4 to 7 to be constantly scanned for pending conversion requests without
the need for external trigger or software action.
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