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The
circuit is built around the PIC IC 16F84A. The circuit is
built as shown above. The power supply of 5V and
ground is given to appropriate pin of the PIC IC and to the H
Bridge circuit. A 4M Hz crystal oscillator (S) is connected as
shown in the figure. Other type of oscillators can also be used.
The crystal oscillator is more stable compare to other types.
Oscillator acts as a clock source for
the PIC IC operation.
The
portB’s four pins are given to the H-Bridge as shown in the
figure. These pins are the control lines (PWM output lines)
given to H-Bridge to rotate in the desired direction and
desired speed.
To
change the direction and speed we need two buttons S1, S2.
These buttons are one side grounded and the other sides are
connected to the pin of the appropriate port of the PIC IC. On
pressing the button S2 the speed is shift between minimum and
maximum .On pressing the button S1 the direction of rotation
is changed either clockwise or anti-clockwise.
FURTHER DEVELOPMENT
On varying the prescalar of the PIC we can achieve different
speeds. For controlling this speed we need to add extra
instruction in the ISR. There are still 3 pins left in the
PORTB which can be used for the control of these speeds.
To handle a motor which requires more power,
high
power transistors or power
amplifiers can be used.
This is the method by which we can control the
motor direction and speed digitally. This allows us to control
the motor without a direct wire connection between control
unit and the motor driving circuit. By using appropriate
communication method this can be achieved.
APPLICATIONS
This project is built with the PIC IC. Hence become more
compact. Here the speed and direction are controlled
digitally. Hence wireless communication between the controller
and the dc driver is possible by adopting suitable methods.
This project can be used wherever there is a DC motor. The
controlling becomes very easy because a very small circuitry
is sufficient.
This can be used in any industrial
applications and in electronic devices, where a DC motor
control is significant. |
