problem in driving the steppermotor

i am getting problem in driving the bipolar steppermotor with l293d in at89s51.what could be the problem?plz help.

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and my l2932 gets hot in few second.how can i cool it?is there available of cooler for l293d also?

In L293D Output Current is 600 mA Per Channel and Peak Output Current can go to about 1.2 A. So if your Stepper drive is rated for some higher current value than this, then L293D will heat up. To support higher currents, you may need to implement both of your H-Bridges using discrete components (Power MOSFETS or stuff like that)

Secondly,to troubleshoot your circuit, check the signals at the output of the microcontroller. After that use an oscilloscope to see whether you are getting the right switching sequence for the motor coils or not.

Proper ON/OFF sequence is necessary to run the motor. Another thing to check for is the frequency of switching. If you're switching at very high frequency your motor may not react to that. These motors are usually low rpm motors.

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In L293D Output Current is 600 mA Per Channel and Peak Output Current can go to about 1.2 A. So if your Stepper drive is rated for some higher current value than this, then L293D will heat up. To support higher currents, you may need to implement both of your H-Bridges using discrete components (Power MOSFETS or stuff like that)

Secondly,to troubleshoot your circuit, check the signals at the output of the microcontroller. After that use an oscilloscope to see whether you are getting the right switching sequence for the motor coils or not.

Proper ON/OFF sequence is necessary to run the motor. Another thing to check for is the frequency of switching. If you're switching at very high frequency your motor may not react to that. These motors are usually low rpm motors.