Technical Data
MC68HC11E Family
—
Rev. 4
216
Analog-to-Digital (A/D) Converter
MOTOROLA
Analog-to-Digital (A/D) Converter
10.6 Channel Assignments
The multiplexer allows the A/D converter to select one of 16 analog
signals. Eight of these channels correspond to port E input lines to the
MCU, four of the channels are internal reference points or test functions,
and four channels are reserved. Refer to
Table 10-1
.
10.7 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.
Table 10-1. 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
Result in ADRx
if MULT = 1
ADR1
ADR2
ADR3
ADR4
ADR1
ADR2
ADR3
ADR4
—
13
V
RH(1)
V
RL(1)
(V
RH
)/2
(1)
Reserved
(1)
1. Used for factory testing
ADR1
14
ADR2
15
ADR3
16
ADR4