VTech Alphabert s Magic Readport User Manual download pdf (Page 60)

Lab Manual of Microcontroller & Interfacing Page 60

EXPERIMENT NO. 14

AIM: Interface stepper motor with port P0 of the microcontroller. Write a program to rotate

motor in clockwise and anticlockwise direction in half step and full step mode.

Circuit diagram:

Interfacing details:

Interfacing of small torque stepper motor with torque of 2Kg-cm is shown in above

diagram. Such motor requires current rating of 0.5 A per phase. Four terminals of the stepper

motor are controlled with PORT P0. As PORT P0 cannot supply desired current, IC ULN 2803

is used to supply necessary drive current to the motor. ULN2803 is high voltage high current

Darlington arrays consists of eight Darlington open collector transistors. Each Darlington pair

can drive load current upto 500 mA. This IC consists of internal suppression diodes for the

inductive loads. These diodes are used to protect switching transistor from breakdown. When

transistor switched from ON to OFF state, large voltage induced across coil of stepper motor can

damage the transistor. The suppression diode discharge energy stored in the inductor when

transistor is in OFF condition.

To drive stepper motor with torque 7 kg-cm, +12V it requires current of 2A/phase. This

stepper motor requires combination of transistor SL-100 and 2N3055 as shown in the following

circuit diagram. Program will remain same. Control signals may come from any port of

microcontroller. In this circuit control signals from port pins P1.0 to P1.3 are shown.

1 2 ... 55 56 57 58 59 60 61 62 63 64 65 ... 79 80

No comments

VTech Alphabert s Magic Readport User Manual Page 60