Registers Format
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3.4 A/D Input Range Control Register
The gain control register is a write-only register using address Base + 9. It is
used to adjust the gain of the analog input programmable amplifier. The data
format is specified as follows:
Address: BASE + 9
Attribute:
write only
Data Format:
Bit
7
6
5
4
3
2
1
0
BASE+9 X X X X X G2
G1
G0
Where G2, G1, and G0 are Gain selection:
G2
G1
G0
GAIN
Input Range (V)
0 0 0 x1
±
5V
Power Up Setting
0 0 1 x2
±
2.5V
0 1 0 x4
±
1.25V
0 1 1 x8
±
0.625V
1 0 0 x16
±
0.3125V
1 0 1 Invalid
X
1 1 0 Invalid
X
1 1 1 Invalid
X
The relationship between input voltage range, maximum input voltage and
gain is specified as the equation:
Analog Input Range = Maximum Input Voltage / Gain
