Need help

Hello i need help i have to control a dc motor .. using a parallel port it should control the speed and direction using PWM on assembly .. so can anyone help me

You can't control a motor off the parallel port which supplies very low current. You will have to use an H-bridge to connect to the parallel port.

The H-bridge must match the motor rating or higher.

Connecting a load like a motor directly to the parallel port you'll most likely fry the UART inside your PC, which means a new main board regularly.

Boncuk

ok then i must connect the parallel port to the h bridge then to a motor.. do u knw how ... ? coz i have no idea about it !

some one told me i can use relays and 2 (2n2222) transistors and one power amplifier(tip122) does it work ???

Of course you can use relays driven by transistors.

It's also a matter of motor rating. High current consuming motors and relays are not a wise combination since the contacts will burn out pretty soon.

A better way is using an H-bridge. Check out the data sheet of the L293 in a DIL-16 package.

It is a dual half bridge which can drive motors ranging from 4.5 to 36V at 1A.

The internal logic is easy enough to connect just two signals from the controlling device for L/H, R/H and fast motor stop.

The data sheet also contains a wiring diagram for bidirectional DC-motor control.

Boncuk

thanks man for the info the dc motor plus the lcd worked .. now i need to control them both using a mutliplexer.. or a buffer.. which one is better and which ports i need to connect to both ..
thnx in advance .. u really helped me