13-10-2010, 08:26 PM
This article is presented ny:
Andrew Herzog
Richard Baker
8051 Project:
Automatic Lighting and Visitor Counter
Automatic Lighting and Visitor Counter
Executive Summary
The objective of the project was to create a circuit with an 8051 microcontroller that sensed when an object passed through an infrared receiver’s receive path to automatically turn on lights and count how many times the receive path was blocked. Discussion
To complete the project several smaller circuits were needed to be designed and constructed. The project needed a circuit to pulse an infrared LED at 38 kHz, a circuit to receive the infrared signal, a seven segment LED display circuit, an auto-lighting circuit, and a programming circuit. The project also required code to be written to the 8051 microcontroller to combine all the smaller circuits into an operational system. The 38 kHz generator, Fig. 1-1, was major factor in getting the infrared receiver to operate correctly. A 555 timing chip was used to output a squarewave at 38 kHz for an infrared LED. The generator needed to be completely isolated from the rest of the circuit because it was found that the infrared receiver’s output was similar to Fig. 1-2 at a frequency of 38 kHz. The receiver needed to output a high until an object blocked the infrared signal when it would output a low.
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