Hi there, im with an engineering and trying to build circuits to drive Stepper motors in FULL/HALF step without using any stepper motor IC's (because that would be way too easy !

Now ive managed to get FULL step working using two J-K flip flops, one 555 timer set to about 3Hz and also 4 XOR gates.

Now having difficulty with building the HALF step. Ive had previous attempts at it but i totally forgot to take into consideration all the invalid stated. Used four D flip flops, four AND gates and 74LS157 multiplexer to build that. Now im totally stuck. Does anyone have any suggestions or circuit diagrams showing the half step method without using the Stepper Motor IC's? thanks

Also i can provide what ive done for both FULL and HALF steps if needed

 

Take a look at section 6 of this tutorial - http://www.cs.uiowa.edu/~jones/step/