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ADuC816: Function of ADC1IC and ADC0IC bit in ICON register of ADuC816

What is the function of ADC1IC and ADC0IC bit in ICON the current source
control register?


The ICON sfr controls the current sources available on the ADuC8xx parts with
sigma delta converters such as the ADuC816.  These current sources are intended
to be used with resistive transducers for instance by passing the current
through the transducer and  measuring the resulting voltage with the ADC. 
Alternatively the current can be passed through the transducer in series with a
reference resistor and by measuring both the voltage across the reference
resistor and across the transducer the signal value can be determined by the
ratio of the two measurements.   In this second case the actual value of the
current is not especially critical since it is the ratio of the two values that
is important and not the absolute value.  In the more simple case though the
value of the current is critical since the voltage is proportional to the
current.  For this purpose the parts are trimmed in the factory with a
calibration value which will trim the currents to the expected value of 200uA. 
This trimmed value is enabled by setting the AD0IC and AD1IC bits for the two
currents respectively.