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L
G
R
Analog to Digital Converter
General Release Specification
MC68HC(7)05H12
—
Rev. 1.0
146
Analog to Digital Converter
MOTOROLA
12.6 A/D
Registers
12.6.1 A/D Status and Control Register (ADSCR)
COCO — Conversions Complete
This read-only status bit is set when a conversion is completed,
indicating that the A/D data register contains valid results. This bit is
cleared whenever the A/D status/control register is written and a new
conversion automatically started, or whenever the A/D register is
read. Once a conversion has been started by writing to the A/D
status/control register, conversions of the selected channel will
continue every 32 cycles until the A/D status/control register is written
to again. In this continuous conversion mode the A/D data register will
be filled with new data, and the COCO bit set, every 32 cycles. Data
from the previous conversion will be overwritten regardless of the
state of the COCO bit prior to writing.
ADRC — RC Oscillator On
When ADRC is set, the A/D section runs on the internal RC oscillator
instead of the CPU clock. The RC oscillator requires a time t
RCON
to
stabilize, and results can be inaccurate during this time. See
Section 12.5 Internal and Master Oscillator
.
ADON — A/D On
When the A/D is turned on (ADON = 1), it requires a time t
ADON
for
the current sources to stabilize, and results can be inaccurate during
this time. This bit turns on the charge pump.
$004F
Bit 7
6
5
4
3
2
1
Bit 0
Read:
COCO
ADRC
ADON
0
CH3
CH2
CH1
CH0
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 12-1. A/D Status and Control Register (ADSCR)