Analog-to-Digital (A/D) Converter
Conversion Process
MC68HC11E Family
—
Rev. 4
Technical Data
MOTOROLA
Analog-to-Digital (A/D) Converter
215
DLY
—
Enable Oscillator Startup Delay Bit
0 = The oscillator startup delay coming out of stop is bypassed and
the MCU resumes processing within about four bus cycles.
1 = A delay of approximately 4000 E-clock cycles is imposed as the
MCU is started up from the stop power-saving mode. This
delay allows the crystal oscillator to stabilize.
CME
—
Clock Monitor Enable Bit
Refer to
Section 5. Resets and Interrupts
.
Bit 2
—
Not implemented
Always reads 0
CR[1:0]
—
COP Timer Rate Select Bits
Refer to
Section 5. Resets and Interrupts
and
Section 9. Timing
System
.
10.5 Conversion Process
The A/D conversion sequence begins one E-clock cycle after a write to
the A/D control/status register, ADCTL. The bits in ADCTL select the
channel and the mode of conversion.
An input voltage equal to V
RL
converts to $00 and an input voltage equal
to V
RH
converts to $FF (full scale), with no overflow indication. For
ratiometric conversions of this type, the source of each analog input
should use V
RH
as the supply voltage and be referenced to V
RL
.