Datasheet
Data Sheet ADuC845/ADuC847/ADuC848
Rev. C | Page 45 of 108
ADC1CON (AUXILIARY ADC CONTROL REGISTER) (ADuC845 ONLY)
ADC1CON is used to configure the auxiliary ADC for reference, channel selection, and unipolar or bipolar coding. The auxiliary ADC is
available only on the ADuC845.
SFR Address: D3H
Power-On Default: 00H
Bit Addressable: No
Table 27. ADC1CON SFR Bit Designations
Bit No. Name Description
7 ––– Not Implemented. Write Don’t Care.
6 AXREF Auxiliary (ADuC845 only) ADC External Reference Bit.
Set by the user to enable the auxiliary ADC to use the external reference via REFIN±.
Cleared by the user to enable the auxiliary ADC to use the internal band gap reference.
Auxiliary ADC cannot use the REFIN2± reference inputs.
5 AUNI Auxiliary (ADuC845 only) ADC Unipolar Bit.
Set by the user to enable unipolar coding, that is, zero input results in 000000H output.
Cleared by the user to enable bipolar coding, zero input results in 800000H output.
4 ––– Not Implemented. Write Don’t Care.
3, 2, 1, 0 ACH3, ACH2, ACH1, ACH0 Auxiliary ADC Channel Select Bits. Written by the user to select the auxiliary ADC channel.
ACH3 ACH2 ACH1 ACH0
Selected Auxiliary ADC Input
Range (V
REF
= 2.5 V).
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 (not a valid selection on the MQFP package)
1 0 0 1 AIN10–AINCOM (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
Temperature Sensor
1
1 1 1 1
AINCOM
–AINCOM
1
Note the following about the temperature sensor:
When the temperature sensor is selected, user code must select the internal reference via the AXREF bit and clear the AUNI bit (ADC1CON.5) to select bipolar coding.
Chop mode must be enabled for correct temperature sensor operation.
The temperature sensor is factory calibrated to yield conversion results 800000H at 0°C (ADC chop on).
A +1°C change in temperature results in a +1 LSB change in the ADC1H register ADC conversion result.
The temperature sensor is not available on the ADuC847 or ADuC848.