XC886/888CLM
Analog-to-Digital Converter
User’s Manual
16-15
V1.3, 2010-02
ADC, V 1.0
16.4.5.2
Request Source Control
All conversion pending bits are ORed together to deliver an intermediate signal PND for
generating REQCHNRV and REQPND. The signal PND is gated with bit ENGT, allowing
the user to enable/disable conversion requests. See
.
Figure 16-7
Parallel Request Source Control
The load event for a parallel load can be:
•
External trigger at the input line REQTR. See
•
Write operation to a specific address of the conversion request control register.
See
•
Write operation with LDEV = 1 to the request source mode register.
See
•
Source internal action (conversion completed and PND = 0 for autoscan mode).
See
Each bit (bit x, x = 4 - 7) in the conversion request control/pending registers corresponds
to one analog input channel. The bit position directly defines the channel number. The
bits in the conversion request pending register can be set or reset bitwisely by the arbiter:
•
The corresponding bit in the conversion request pending register is automatically
reset when the arbiter indicates the start of conversion for this channel.
•
The bit is automatically set when the arbiter indicates that the conversion has been
aborted.
A source interrupt can be generated (if enabled) when a conversion (requested by this
source) is completed while PND = 0. These rules apply only if the request source has
triggered the conversion.
conversion request control register
LDE
. . .
conversion request pending register
bitwise OR
parallel load
PND
AND
REQPND
REQCHNRV
data written
by CPU
bitwise
set/reset
by arbiter
0
1
ENGT
rw
1
0
rwh
rwh
*