Here we use PIC16F72 controller to control the electric bicycle system. In this electric
bicycle system some components are installed such as brushless dc motor, PIC controller,
battery and dynamo, so here required to controller for controlling the different component
of electric bicycle system.

There are different functions of this controller such as under voltage protection, over
current protection, control power supply, also to drive and control the Brushless dc motor.

There are different signal were transmitted to pin of PIC controller to drive and control
brushless dc motor, such as current detection signal, motor speed control signal, capacity
detection system.

In this PIC16F72 controller has 28 pins, 22 I/O pins that are user configurable on a
pin-to-pin basis. There are 35 number of instruction in this PIC controller.

The operating frequency is 20 MHz Also in this controller there are three I/O port are use
such as PORTA, PORTB and PORTC and three Timers are use Timer0, Timer1 and Timer2.

In this pin diagram RA1, RA4 and RA5 pin there are transmitted speed control, helping signal,
current detection signal.

The current detection signal use here because, if any heavy current situation electric
bicycle is running at heavy load the current is increasing in motor. Then it will be
damages winding of motor and component of motor.

Here required current detection signal for controlling the current. Also there are under
voltage protection is required because of avoid the low voltage supply, which is affect on
electric bicycle running normally, then controller should be provide capacity checking.

The voltage consists with resistance then it transmitted to PIC controller. If voltage
supply signal transmitted to PIC controller then checking supply voltage.