54
The Practical circuit
The practical circuit consists of two-step drives (12V DC), by step angle
(0.5) degree, and display screen (LCD) with the size of (20*2), for displaying the
different modes of the tracking system. A set of light dependent resistor (LDR)
that have been linked with resisters to make voltage divider circuit and to produce
an income signal for the microcontroller. A set of switches type (Slotted Opto
switches) and two current drive circuits (ULN2003) to control the feeding access
to the two stepper motors or to separate the feed from the two-stepper motors.
The drive circuit is in the middle, between
the stepper motor and the
microcontroller
The four light dependent resistors (sensors) were connected in (PORTA),
where the southern and northern light sensors were connected (PORTA.1
PORTA.0). While the eastern and western light sensors are connected to
(PORTA.3, PORTA.2). The display (LCD) is also connected in (PORTC). The
stepper motor which is responsible for the movement
in the southern and
northern directions was plugged into the upper part of the (PORTD) through
current drive circuit (ULN2003). Moreover, the stepper
motor responsible for
the movement in the eastern and western directions was plugged into (PORTB)
through current drive circuit also. The three keys (slotted Opto switches) were
connected to the other (PORTB), where the top key (switch up) was connected
in (PORTB.5), the lower key (switch down) is in (PORTB.4) and the key placed
in the base (base switch), is plugged in (PORTB.6).
(5V DC) was used to feed the micro controller and the ADC in PORTA.
In addition, the stepper motors were connected to 12V
DC through adapter
voltage as in the figure 5.1.
