If you use a chip like the ULN2003 you're limited to uni-polar steppers; if you use the L293D (or equivalent, like the SN754410NE) instead, you can run uni-polar and bi-polar motors with the same code.
If you use a chip like the ULN2003 you're limited to uni-polar steppers; if you use the L293D (or equivalent, like the SN754410NE) instead, you can run uni-polar and bi-polar motors with the same code.