before I try and describe my problem here's the list of parts I'm using.
Big Easy driver - http://www.schmalzhaus.com/BigEasyDriver/
Colour LCD shield - https://www.sparkfun.com/products/11062
400 step/rev stepper - https://www.sparkfun.com/products/10846
I'm building an automatic guitar pickup coil winder. not the first time its been done for sure, but I've got my own share of problems developing mine.
basically, I can run the motor comfortably up to 500rpm. it starts to get a bit "sketchy" at about 575/600rpm.
all my programming for user input is complete, the user is able to set the speed (in RPM), the number of Turns, usually up to 10000 possibly more (each turn is a full revolution of the stepper), and the guage for the magnet wire being used. I'd also like to display on the LCD the "Status" being one of the following, "Ramp Up" "Running" and "Cool Down". ramp up and cool down being steady increase/decrease in speed for both stability of the stepper and so there's no sudden jerks on the copper wire. I'd also like to display the number of turns remaining.
my problem is, that as soon as I try and do anything else while the stepper is running at a decent speed the arduino seems to take too long to process before the next instruction to be sent to the stepper and then the stepper will seize. even a simple "Serial.println(output);" will make the stepper jerk at 500rpm.
I'm only trying to update a single line of text on the LCD at the moment, changing "Ramp Up" to "Running" as soon as the stepper reaches 500rpm but this causes it to seize.