Thursday, November 25, 2010

Stepper Motor: Half Stepping

Stepper motors can be energized in two ways. One is by energizing a single coil at a time. Other is by energizing two coils at a time. In the latter case more torque is obtained. In the previous examples we used single coil excitation. By combining two above two ways of excitations, stepper motors can be operated in two modes.

  • Full step mode.
  • Half step mode
In full step mode stepper motor will be rotating by a specific angle specified by the manufacturer. But in half stepping mode, it will take only half steps. Thus we could increase the resolution of the stepper. Here a program for working stepper motor in half stepping mode is written in Turbo C++. Algorithm is as follows.

Initially a single coil is exited and rotor gets locked with coil. Next keeping the current coil excited the adjacent coil is also excited. Thus the rotor cannot get into lock with any single coil, instead it will be held in a position between the coils. This makes a half step. Now the first coil is de energized keeping the second coil energized. Like wise when this is looped the stepper makes half steps.

Again interface circuit is same as in the previous examples.


Anonymous said...

pin 2 and 5 of the stepper remain 12 V, the rest of the pin has voltage around 0.8 to 0.2 V

not dancing at all.

dmesg | grep 378, found 378... can u tell me how to perform diagnose? please

Anonymous said...

no, it does not move and it burns the uln 2003 chip with smoke. may be the motor is too big, need a lot of current to drive it!

Anonymous said...

I have replaced a new uln 2003 chip, and checked all connections in both chips before powering up with 5V and 12V; I measured all output voltages at pin 16, 15, 14,and 13 while I executed ./stepper_1 at root account( compiled). This is done without connecting to stepper motor. There is dancing of voltage at all.

Anonymous said...

I used a fluke meter to measure the stepper motor and find out the following

pin 1
pin 3
pin 6 are connected

pin 2
pin 4
pin 5 are connected

the above was checked again and again and again before I soldered header.

Anonymous said...

stepper motor

pin 3 and pin 4 are supplied with 12V.

Anil C S said...

please specify the model of your stepper motor. The circuit which I posted is compatible only with FDK J58A832T stepper motor. If you are using any other model it wont work.

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