H-BRIDGE interfacing with parallel port

H-BRIDGE interfacing with parallel port
This tutorial is taken from the book MY EXPERIENCE IN PARALLEL PORT INTERFACING. you can download it free from the files section(file:-parallelport(3 files) of yahoo group-booksbybibin http://groups.yahoo.com/group/booksbybibin/ comments about this book on www.booksbybibin.blogspot.com H-BRIDGE

See the circuit diagram above you will get it. For forward motion transistors (1,3) should be ON and remaining (2,4) OFF. For Backward motion transistors (2,0) should be ON and (1,3) should be OFF. For stopping(0,0) condition of H-bridge, Transistors(1,3) should be ON and (0,3) should be OFF. For braking(1,1) transistors (1,2) should be ON and (0,3) should be OFF. So make a programm according to this to turn motor forward,backward,brake.


#include"bparlib.c"
void main()
{
int a;
printf("stop : 0 \n forward : 1\n backward : 2\n  brake: 3\n");
printf("enter the value");
scanf("%d",&a);
Write_DataPort(0x00); //to avoid malfunctioning and short circuit of supply

switch(a)
{
case 0:
	printf("motor is stopped (0,0) of H-bridge");
	Write_DataPort(0x00); //to clear all other bits
	Set_DataPort_bit(0);
	Set_DataPort_bit(3);

case 1:
	printf("motor is moving forward(0,1)");
	Write_DataPort(0x00); //to clear all other bits
	Set_DataPort_bit(1);
	Set_DataPort_bit(3);
	break;

case 2:
	printf("motor is moving backward(1,0)");
	Write_DataPort(0x00); //to clear all other bits
	Set_DataPort_bit(2);
	Set_DataPort_bit(0);
	break;
case 3:
	printf("motor is braked(1,1)");
	Write_DataPort(0x00); //to clear all other bits
	Set_DataPort_bit(1);
	Set_DataPort_bit(2);
	break;
default:
	break;
	}
	getch();
}

see not to short circuit Vcc and power supply by making (2,3) ON, first condition and (0,1) ON another condition when Vcc is connected to ground and short circuit occurs. But if you use power transistor then the heat sink will get heated too much. adapter o/p 6.42v,voltage across motor 2.35v.

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