arduino and stepper motor with easy drive help needed!

Hello,

I am making a clock for an school project with all kinds of pointers. I needed a stepper because the pointers are pretty heavy and don't work on a normal quartz framework because they are to heavy.

I want the stepper motor to rotate 360 degrees in 1 minute.. I think its a simple code.. i can experiment with changing the values.. but i used a code form an tutorial but i didn't manage to get it turning really slowly. Someone knows this is possible and can help me?

my stepper motor http://floris.cc/shop/en/motor-servo-solenoid-pump/315-stepper-motor-with-cable.html

Thanks in advance.

Use a easy driver to drive the stepper motor. It is default 1/8 step and for the speed of clock hands you wont need any accelareation. Use a power supply from 12V to 20V for the driver. https://www.sparkfun.com/products/10267
You just need a step signal from the arduino since the direction never changes. If we assume 1/8 step you will need 1600steps/revolution. This resolves to
1600/60 = 26774,667 Hz = 37,5 ms/step for the seconds hand
1600/3600 = 0,444Hz = 2250ms/step for the minutes hand
1600/43200 = 0,0370 Hz = 27000ms/step for the hours hand

You should be aware of that the timekeeping precision of an arduino is not that good so you might consider using a RTC chip as well

You need to be aware that a 200 step motor CANNOT step through 60 even intervals to match with minute or second marks. With 1/8 microstepping (1600 steps per revolution) 1/60th of a revolution would be 26.67 steps so you either have 26 or 27. And if you do 60 separate moves of 26 or 27 steps the clock will go wrong - some need to be 26 and some need to be 27.

The error may not be enough to matter, but if it is you will need to have 3:1 gearing between the motor and the shaft connected to the hands.

...R