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The Analog to Digital Conversion is a quantizing process. Here the analog signal is represented by equivalent binary states. In the first technique it compares given analog signal with the initially generated equivalent signal. In this technique, it includes successive approximation, counter and flash type converters.
In another technique it determines the changing of analog signals into time or frequency. This process includes integrator-converters and voltage-to-frequency converters. The first process is faster but less accurate, the second one is more accurate.
As the first process uses flash type, so it is expensive and difficult to design for high accuracy. It has 8 channel multiplexer to interface with the microprocessor. This chip is popular and widely used ADC. This device uses successive approximation technique to convert analog signal to digital form. Let us see the circuit diagram of connecting , and the ADC converter. The PortA of chip is used as the input port. This port is also used as input port.
The Clower port is used as output port. The PC lines are connected to three address pins of this chip to select input channels. Now let us see a program to generate digital signal from analog data. We are using IN0 as input pin, so the pin selection value will be 00H.
Interface 8255 with 8085 microprocessor for 1’s and 2’s complement of a number
Interface 8255 with 8085 microprocessor for addition