I have to make a voltmter using the 8051. I have thought of using the ADC 0808 to digitise analog voltage. Please explain the logic for the program.
I have the following as mandatory.
1. 4 7 Segment LED displays.
Please help

 

That is a very general statement. You are to use four 7 segment displays. That could indicate 3 1/2 digits (1.999) or something else.

Is this a straight 8051? If so, it will need an interface IC pluse ROM (for the program) and RAM (for the data) memory IC's.

At any rate, the A to D converter has to be able to resolve one part in 2000 - that is the 1.999 volts part. An AD808 is only 8 bits, or one part in 256, which is not nearly enough.

What can your 8051 do? You need to clarify the range of voltages to be able to read, and find an A to D converter that will work with the 8051.

 

Maximum voltage is 2 volts. I need to display 2 0 0 0 for the maximum. So that isn't a 3 1/2 display.

 

Reading 2.000 is not too far off 1.999. What about the rest for the hardware?

 

That would be fine too. I was thinking of multiplexing the displays directly through the controller, only if it is feasible. Otherwise a decoder would work too. But I am stuck at the starting position, how do I put the analog quantity of 2V into the controller. Controller is 8 bit. Will an ADC with more bits help me?