Texas Instruments MSC1210 User Manual
Page 140
Input Multiplexer
12-4
The positive input channel and the negative input channel are selected in the
ADC Multiplexer register (ADMUX, SFR D7h). The high four bits of ADMUX
(bits 4 through 7) select the positive channel, while the low four bits (bits 0
through 3) select the negative channel. The ADMUX SFR has the following
definition:
7
6
5
4
3
2
1
0
Reset Value
SFR D7H
INP3
INP2
INP1
INP0
INN3
INN2
INN1
INN0
01H
INP3-0 (bits 7-4)—Input Multiplexer Positive Channel. This bit selects the
positive signal input.
INP3
INP2
INP1
INP0
Positive Input
0
0
0
0
AIN0 (default)
0
0
0
1
AIN1
0
0
1
0
AIN2
0
0
1
1
AIN3
0
1
0
0
AIN4
0
1
0
1
AIN5
0
1
1
0
AIN6
0
1
1
1
AIN7
1
0
0
0
AINCOM
1
1
1
1
Temperature Sensor (requires ADMUX = FF
H
)
INN3-0 (bits 3-0)—Input Multiplexer Negative Channel. This bit selects the
negative signal input.
INN3
INN2
INN1
INN0
Negative Input
0
0
0
0
AIN0
0
0
0
1
AIN1 (default)
0
0
1
0
AIN2
0
0
1
1
AIN3
0
1
0
0
AIN4
0
1
0
1
AIN5
0
1
1
0
AIN6
0
1
1
1
AIN7
1
0
0
0
AINCOM
1
1
1
1
Temperature Sensor (requires ADMUX = FF
H
)
Therefore, to select AIN1 as the positive channel and AIN6 as the negative
channel, the following assignment would be made to the ADMUX register:
ADMUX = 0x16h; // 0001=AIN1, 0110=AIN6
By default, ADMUX defaults to 01
H
at power up, so AIN0 is the default positive
input and AIN1 is the default negative input.