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Channel positioned TV antenna

System design - Hardware

The prototype was created based on the final product and certain features of the product deferred from the actual product which is mentioned in earlier chapters. The noteworthy changes from the final product would be described below;

  • Driver Unit
    • Driver Unit consist a potentiometer which has the capability to rotate only 270deg.
    • The stepper motor used would be smaller than that of the final product which would have the ability to hold the weight of the antenna.
    • The two components would be connected directly by placing one top of another rather than using a gear wheel.
  • Control box
    • The program logic for the microcontroller would be the same but the final code would differ from the code of the prototype as hardware changes would be made (keypad replaces remote controller).
    • The IR receiver would not be included in the controller unit.
    • The Display Unit would only consist of a single seven segment display as the program is designed for only three positions.
    • Power cannot be given directly through a wall outlet therefore a DC power supply was used for this task.
  • Controller Unit
    • The use of a remote controller was replaced by 4x4 matrix keypad as this would simplify the task of programming for the prototype.
    • The functions would also be limited which is indicated in the following diagram;

Prototype block diagram

In the process of creating any product the easiest method to communicate the concept of the product is through a block diagram. Following is the block diagram which was created for the prototype;

 

  • Hardware components
    • Microcontroller 16F877A – This would perform the task of processing data and executing required functions (e.g. rotate antenna, Process key press). This requires an operating voltage of 5V.
    • Stepper Motor – This would be rotating the antenna as it receives the pulses from the microcontroller. The operating voltage is 5V, which could change depending on the stepper motor that is chosen to build the product.
    • 10KΩ Variable Resistor – This device would be connected to the stepper motor and rotates as the stepper motor rotates. This devise is supplied 5V and act as a voltage divider. Varying values of voltage would be inputted to the microcontroller, which would be used to determine the position.
    • 4x4 Matrix Keypad – This is the interface for the control box where functions required must be performed by the push of a button. The button pressed would be inputted to the microcontroller.
    • Seven Segment- This would be used for character display of a particular button pressed.
    • ULN2804A – The transistor array would be used as the microcontroller cannot provide the large current which the stepper motor requires.
    • Breadboard – The Circuit would be mounted on the following device.
    • Power Supply – A power supply would be used which would be set to 5V at all times.
    • Assisting components – Standard lab components used.

The Prototype