I have a question about how to to connect a stepper shield to an arduino card in a specific way to control a bipolar stepper motor. I'm actually using a DFRobot MD1.3 shield (specs are here : MD1.3_2A_Dual_Motor_Controller__SKU__DRI0002_-DFRobot) which need to be connected to arduino with four pins. I need to connect to arduino in a different way, like with the Big Easy shield from sparkfun, with only two pins (like here : Big Easy Driver stepper motor driver), one for direction control and one for step control . I can't figure out how to do that, i don't even know if it is possible. Could anyone help me ?
You can't drive this board with only direction and step; that takes more logic or a special chip like the EasyDriver.
You CAN reduce the number of pins to one for each motor winding (two total) IF you will only single-step the stepper. In that case you need to add an external Inverter chip between each set of two motor driver pins so that those pins are always opposite polarity.
Typically you'd use a 74HC14 or 74LS14 or equivalent "Hex Inverter" chip (Which has 'hex' that is 6 inverters in a package).