Freescale Semiconductor, Inc.
10.4 Channel Assignments
The multiplexer allows the A/D converter to select one of sixteen analog signals. Eight
of these channels correspond to port E input lines, four of the channels are internal
reference points or test functions, and four channels are reserved. Refer to Table 10-
1.
Table 10-1 A/D Converter Channel Assignments
Channel
Number
Channel
Signal
Result in ADRx if
MULT = 1
1
2
AN0
AN1
ADR1
ADR2
ADR3
ADR4
ADR1
ADR2
ADR3
ADR4
—
3
AN2
4
AN3
5
AN4
6
AN5
7
AN6
8
AN7
9
Reserved
Reserved
Reserved
Reserved
10
11
12
13
—
—
—
V
*
ADR1
RH
14
15
16
V
*
ADR2
ADR3
ADR4
RL
(V )/2*
RH
Reserved*
*Used for factory testing
10.5 Single-Channel Operation
There are two types of single-channel operation. When SCAN = 0, the first type, 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 com-
mand is written to the ADCTL register. In the second type of single-channel operation,
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.
10.6 Multiple-Channel Operation
There are two types of multiple-channel operation. When SCAN = 0, the first type, 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 com-
mand is written to the ADCTL register. In the second type of multiple-channel opera-
tion, 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.
ANALOG-TO-DIGITAL CONVERTER
MC68HC11F1
10-6
TECHNICAL DATA
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