MC68HC705P9 Datasheet, PDF (128/156 Pages) Motorola, Inc – HCMOS Microcontroller Unit

ADC _{I/O Registers}
CH[2:0] — Channel Select Bits
These read/write bits select one of eight ADC input channels as
shown in Table 3. Channels 0–3 are the input pins, PC3/AN3,
PC4/AN2, PC5/AN1, and PC6/AN0. Channels 4–6 can be used for
reference measurements. Channel 7 is reserved for factory testing.
Table 3. ADC Input Channel Selection
CH[2:1:0]
000
001
010
011
100
101
110
111
Channel
0
1
2
3
4
5
6
7
Signal
AN0
AN1
AN2
AN3
V_RH
(V_RH + V_SS) / 2
V_SS
Reserved
To prevent excess power dissipation, do not use an ADC pin as an
analog input and a digital input at the same time.
Using one of the port pins as the ADC input does not affect the ability to
use the remaining port pins as digital inputs.
Reading a port pin that is selected as an analog input returns a logic
zero.
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128
ADC
MOTOROLA