Datasheet

ADuC845/ADuC847/ADuC848 Data Sheet
Rev. C | Page 44 of 108
ADC0CON2 (PRIMARY ADC CHANNEL SELECT REGISTER)
ADC0CON2 is used to select a reference source and channel for the primary ADC.
SFR Address: E6H
Power-On Default: 00H
Bit Addressable: No
Table 26. ADC0CON2 SFR Bit Designations
Bit No. Name Description
7, 6 XREF1, XREF0 Primary ADC External Reference Select Bit.
Set by the user to enable the primary ADC to use the external reference via REFIN± or REFIN2±.
Cleared by the user to enable the primary ADC to use the internal band gap reference (V
REF
= 1.25 V).
XREF1 XREF0
0 0 Internal 1.25 V Reference.
0 1 REFIN± Selected.
1 0 REFIN2± (AIN3/AIN4) Selected.
1
1
Reserved.
5 ––– Not Implemented. Write Don’t Care.
4 ––– Not Implemented. Write Don’t Care.
3, 2, 1, 0 CH3, CH2, CH1, CH0 Primary ADC Channel Select Bits. Written by the user to select the primary ADC channel as follows:
CH3 CH2 CH1 CH0 Selected Primary ADC Input Channel.
0
0
0
0
AIN1–AINCOM
0 0 0 1 AIN2–AINCOM
0 0 1 0 AIN3–AINCOM
0 0 1 1 AIN4–AINCOM
0 1 0 0 AIN5–AINCOM
0 1 0 1 AIN6–AINCOM
0
1
1
0
AIN7–AINCOM
0 1 1 1 AIN8–AINCOM
1 0 0 0
AIN9–AINCOM (LFCSP package only; not a valid selection on the MQFP
package)
1 0 0 1
AIN10–AINCOM (LFCSP package only; not a valid selection on the MQFP
package)
1 0 1 0 AIN1–AIN2
1 0 1 1 AIN3–AIN4
1 1 0 0 AIN5–AIN6
1 1 0 1 AIN7–AIN8
1 1 1 0
AIN9–AIN10 (LFCSP package only; not a valid selection on the MQFP
package)
1 1 1 1 AINCOM–AINCOM
Note that because the reference-detect does not operate on the REFIN2± pair, the REFIN2± pins can go below 1 V.