DC Motor is an electromechanical device which converts electrical energy into mechanical energy. We can control two parameters of the DC motor. First parameter is speed and second is torque. These parameters can be controlled using the appropriate DC motor such as series motor, shunt motor etc. DC motors requires high current to fulfill the demand of stator coil & rotor coils. This current would be greater than 100mA if we consider the small DC motors. As we know that 8051 microcontroller can sink or source maximum 10mA of current on any port pin. So to boost the current level to meet the requirement of the DC motor we need to use motor driver IC L293D which can source 600mA typical current & 1A maximum current on its single output pin.
DC motors can be operated as Start/Stop where direction of rotation is fixed and/or speed is controlled and forward/reverse direction mostly in robotic applications.
L293D Truth Table
|Inputs (VCC1 (Voltage at Pin 16) or GND)||Output (VCC2 (Voltage at Pin 8) or GND)|
|X||0||Z (High Impedance)|