Stepper motor issue

Hi all so i am building a 3d printer of my own. So far i have Sanguinololu 1.3a and extruder with 1 stepper motor. I think i programmed the chip on the board properly. When i test the heat bed and extruder temperatures i am able to reach them and the board is controling this temp. When i connect the stepper motor to the board i see behaviour that concerns me. What happens is that i can move the motor in one direction with the smaller steps. If i try the bigest step or reverse i hear some whistling sound from the motor itself. I wonder if this is due to lack of voltage. I have connected the board to 12V pc power supply as i think it should be. Any advise will be appritiated.

PS. Could it be a driver issue? I bought the stepper mottor drivers with the board itself.

Edited 1 time(s). Last edit at 06/24/2014 02:43AM by ts87.

If the firmware upload was ok or not, thats not a matter of guessing, the arduino will verify the upload and give you an "ok" message at the end, if you can read that then its ok.

When the motor can move slowly to one direction and not to the other direction, thats a typical situation of a wrong endstop configuration. What happens is the firmware thinks the endstop is triggered, so it will try run the opposite direction to escape from it. So it will move to one direction at slow speed, while it will refuse to move to the other direction because it thinks that the direction where triggered endstop is. Try re-check your endstops configuration.

Thank you for the answer. I actually have not connected the 3 endstop switches yet. I was just testing the board with different components, but the switches i have not tested yet. If i understand you properly i should connect them and proceed the testing when everything is connected.

The mechanical endstops normally work by using NC, meaning they always sink the 5v from pin to gnd, and the firmware is able to read 0v on its pin. If they get triggered they disconnect the line and the pin jumps to 5v. So ofc that if endstops are missing, that is exactly same thing as them being triggered. So yes connect the endstops and test everything when its completed.

Thank you. As i said i am new in this, but i appritiate the help I will post the result when i test.

I did the test with the end stops and it works ok now I guess the only thing left is to assemble the whole thing, calibrate and start printing