Microcontroller Based Voltage Measurement

Topics: Analog-to-digital converter, Microprocessor, Input/output Pages: 12 (2291 words) Published: July 16, 2012

Aniruddh Dey – 000611501010
Manoranjan Kumar Choudhary – 000611501017
Nilabh Gupta – 000611501022
Gaurav Bagla – 000611501028
Nilay Mitash – 000611501036
Power Engineering
4th Year
Jadavpur University

I would like to offer my sincere gratitude to Professor Gargi Konar, who has contributed to this project in a major way. I thank her for her guidance and support during the project with her immense expertise and cooperation on the topic.

Date: 08.05.2010


The objective of this project is to design a circuitry and interfacing it with microcontroller so as to get the digital output for an analog input. We are sensing voltage under this project. The basic components include the use of ADC 0809 and interfacing it with 8051 microcontroller through 8255 peripheral. There are 8 select channels, IND to IN7 through which we can provide an analog input to ADC which we have obtained from an analog device. This output can be electrical signals of transducers measuring temperature, depth, pressure, etc. in the form of an output voltage. We see that there are 8 input channels for ADC and we can use 8 different inputs at a time. Now the output of this ADC is fed into the input of 8051 micro controller. Through a 8255 peripheral. The microcontroller the displays this digitized output on a screen which we can see. We write a program in the microcontroller which then controls the functioning of sending signals to ADC and receiving the output from ADC. The program generates signals which activate the ADC.

The digitized output if microcontroller can be used for various purposes, like in power plants we can use this for continuous voltage monitoring of a generator, continuous temperature sensing in various parts of boiler, etc. We can use these outputs for other purposes also according to our requirements. 2. HARDWARE CIRCUITRY

1. Block Diagram


Fig. 2.1.1 Block Diagram
2. Circuit Explanation

Fig. 2.2.1 Circuit Diagram

We have taken a 9-0-9 V transformer and we are passing the secondary voltage into a positive voltage regulator(7805).This is giving us a regulated supply of +5v which is fed into the VCC of ADC0809.The ADC0809 has been connected to the 8051 microcontroller through 8255 peripheral by a RELEM connector. Now this microcontroller sends activation signals toADC0809 .IN0 pin is selected through select lines and the analog voltage input from potentiometer is fed into IN0.The connection is done to take the digitized output from ADC into the microcontroller which is further displayed on screen. 3. Analog to Digital Converter (ADC)

[pic] [pic]

Fig. 2.3.1 ADC 0809 Fig. 2.3.2 Electric Symbol

An analog-to-digital converter (abbreviated ADC, A/D or A to D) is a device which converts continuous signals to discrete digital numbers. The reverse operation is performed by a digital-to-analog converter (DAC). Typically, an ADC is an electronic device that converts an input analog voltage (or current) to a digital number proportional to the magnitude of the voltage or current. The digital output may use different coding schemes, such as binary, Gray code or two's complement binary. Resolution

The resolution of the converter indicates the number of discrete values it can produce over the range of analog values. The values are usually stored electronically in binary form, so the resolution is usually expressed in bits. In consequence, the number of discrete values available, or "levels", is usually a power of two. For example, an ADC with a resolution of 8 bits can encode an analog input to one in 256 different levels, since 28 = 256. The values can represent the ranges from 0 to 255 (i.e. unsigned integer) or from -128 to 127 (i.e. signed integer), depending on the...
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