Am I stretching the limits of a single Uno?

Hey all,

I'm new to Arduinos, which I will be using to control an automated apparatus. Ideally, I want to control/read a number of things simultaneously, all through the Arduino.

-Two stepper motors. These are essential. (http://www.sparkfun.com/products/9238) - 12V. -Input from two photodiodes. I'd also like to power two small LEDs that work with these, but I can do that externally if necessary. -Control two syringe pumps. A modified version of this: (http://www.med-associates.com/pumps/phm100.htm) Most of the power for these is external (28V). Essentially, I've rigged them up so that can communicate to them with a single wire. If it's at +5V, the pump won't turn. If it's grounded, it turns, which means I'll need to link it to the same ground as the arudino, right? -A servo motor to open/close a door.

I bought a couple of Arduino Unos, two steppers (http://www.sparkfun.com/products/9238), two easy drivers (http://www.sparkfun.com/products/10267), as well as Adafruit's motor shield, to try out different things. I don't fully understand the mapping of the ports yet, either on Uno, EasyDriver, or AdaFruit shield, but I'm reading up on that now. If someone could give me a bit of feedback to point me in the right direction, it'd be much appreciated.

Thanks B

which means I'll need to link it to the same ground as the arudino, right?

You always need a common ground, see:- http://www.thebox.myzen.co.uk/Tutorial/Power_Supplies.html

Read up on the two types of stepping motor:- http://www.thebox.myzen.co.uk/Workshop/Motors_3.html and http://www.thebox.myzen.co.uk/Workshop/Motors_4.html

As long as you don't run the motors from board power you should be good and not pushing limits. Limits of your patience, at times perhaps. Even real slow things like analog read take about 1/10th of a millisecond.