  Data acquisition is an important process in the functioning of any control
system. Usually, the acquired signal is analogic, representing a continuous
physical measure, and it should be processed in a digital system based on an
analog to digital converter (ADC) and a microcontroller. The ADC provides the
converted value in ADC units, but the system and its operator need the value
expressed in physical units. In this paper we propose a novel design solution
for the scaling module, which is a key component of a digital measurement
system. The scaling module refers to fitting the sensor result of a variable
number of bits depending on the ADC resolution into physical units. A general
method for scaling is proposed and a SageMath script is presented for obtaining
easily the scaling function. In the last part of the paper, the proposed method
is validated in a case study, by calculus, and it is implemented on a low-cost
development system in order to create a wireless sensor node.
