try this pattern - 1000 0010 0100 0001Arduino pins 2 & 3 are controlling 1 winding. pins 3 and 4 are controlling the other winding. So the motor is buzzing becase you start in one direction with pin 2 and then immediately reverse it with pin 3.OR - try wiring it this way - Arduino -2 to LM293 -2, Arduino -3 to LM293 -10, Arduino -4 to LM293 -7, Arduino -5 to LM293 -15, and use your original output pattern.
Change the code to issue one step at a time and check the voltages going to the windings - at least one must be wrong.
Quote from: MarkT on Jan 16, 2013, 11:41 pmChange the code to issue one step at a time and check the voltages going to the windings - at least one must be wrong.He is using a bi-polar motor using a double h-bridge.