Analog-to-Digital (A/D) Converter
Data Sheet
M68HC11E Family — Rev. 5
68
Analog-to-Digital (A/D) Converter
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MOTOROLA
3.6 Single-Channel Operation
The two types of single-channel operation are:
1.
When SCAN = 0, the single selected channel is converted four consecutive
times. The first result is stored in A/D result register 1 (ADR1), and the fourth
result is stored in ADR4. After the fourth conversion is complete, all
conversion activity is halted until a new conversion command is written to
the ADCTL register.
2.
When SCAN = 1, conversions continue to be performed on the selected
channel with the fifth conversion being stored in register ADR1 (overwriting
the first conversion result), the sixth conversion overwriting ADR2, and so
on.
3.7 Multiple-Channel Operation
The two types of multiple-channel operation are:
1.
When SCAN = 0, a selected group of four channels is converted one time
each. The first result is stored in A/D result register 1 (ADR1), and the fourth
result is stored in ADR4. After the fourth conversion is complete, all
conversion activity is halted until a new conversion command is written to
the ADCTL register.
2.
When SCAN = 1, conversions continue to be performed on the selected
group of channels with the fifth conversion being stored in register ADR1
(replacing the earlier conversion result for the first channel in the group), the
sixth conversion overwriting ADR2, and so on.
Table 3-1. Converter Channel Assignments
Channel
Number
1
2
3
4
5
6
7
8
9 – 12
Channel
Signal
AN0
AN1
AN2
AN3
AN4
AN5
AN6
AN7
Reserved
V
RH(1)
V
RL(1)
(V
RH
)/2
(1)
Reserved
(1)
Result in ADRx
if MULT = 1
ADR1
ADR2
ADR3
ADR4
ADR1
ADR2
ADR3
ADR4
—
13
1. Used for factory testing
ADR1
14
ADR2
15
ADR3
16
ADR4
F
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