Step – Motor Indexing Control by Using Audio Card

Step-Motor is a kind of important drive element in automatic control of machines (NC machine tools etc.). Many researchers have pointed out that the audio card could be applied in many fields such as data acquisition, motor control etc. Its advantages : no driving program needed to write, good compatibility with operation system and no update problem of the driving program etc. The important characters of the audio card, continuity and synchronism, are important in data acquisition and also in the lead control of the step motor. The output of the DA audio card could be used to produce the lead control signal for the step motor. In this paper the CMI8738 chip is used as an example to show the principle and the method to produce the impulse frequency, port circuit and correspondent programming. The experiment has proved that it could be used to lead control synchronously a six-channel step motor, the maximum impulse frequency of each channel could be reached to 24 kHz. At last the problem to use directly the usual audio card for lead control was discussed.