Interfacing the Microprocessor with Analog World: As computer used digital binary values whereas we have physical variables, a step by step process is used to convert the physical variable to binary data and again to physical variable. The figure is given below
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(i) Transducer: A transducer is a device that converts the physical variable to an electrical variable. The output of the transducer is an analog current or voltage that is proportional to the physical variable. Supposing water temperature is varying from 800F to 1500F, it may be outputted by the transducer as 800mV to 1500mV.
(ii) Analog to Digital Converter (ADC): The ADC takes the output of the transducer as its analog input and converts it to a digital data. For example, the ADC might convert the 800mV to 1500mV to binary value ranging from 01010000 (80) to 10010110 (150).
(iii) Computer: Now the digital output of ADC will taken into the digital processor or computer to process it in a predefined way. It will calculate or operate the input in a predefined way and will produce a digital output.
(iv) Digital to Analog Converter (DAC): The digital output of the computer will be taken as input by the DAC. This will convert the digital data to an analog electrical signal. For example, the computer might produce 00000000 to 11111111 which the DAC converts to 0V to 10V.
(v) Actuator: Sometimes DAC is connected to some device that controls the physical variable called actuator.