I’ve got simple requirements for my NEMA17 stepper motor and uStepper controller, but I can’t get it to do what I want. I’m completely new to Arduino.
My requirements are:
Move a carriage 20cm in one direction (CCW) over 8 hours;
Move the carriage 40 cm in the opposite direction (CW) EITHER over 8 hours, or if possible just quickly and then pause for eight hours;
Move the carriage 20cm in one direction (CCW) back to the middle point over 8 hours.
Repeat
The reason for the repeat of steps 1 and 3 are that I need this to run from 6:00 - 22:00, then return to the start position. By starting the code in the middle I can set the experiment running at 14:00 rather than 6:00. This experiment should run continuously for four months.
According to the documentation, the NEMA17 stepper motor has 200 steps/rev, having from testing it it seems to be around 3200. Ideally I’d want a precise number, perhaps using moveAngle instead if I don’t know the step number.
Either way, I can’t get this simple code to work, and any help would be very appreciated!
Here’s what I’ve got:
#include <uStepper.h>
uStepper stepper;
void setup() {
// put your setup code here, to run once:
stepper.setup();
Serial.begin(115200);
}
void loop() {
// put your main code here, to run repeatedly:
stepper.setMaxVelocity(0.37037);
stepper.moveSteps(10667, CCW, HARD);
stepper.setMaxVelocity(0.74074);
stepper.moveSteps(21334, CW, HARD);
stepper.setMaxVelocity(0.37037);
stepper.moveSteps(10667, CCW, HARD);
}
If you don't know how many steps the motor has then how is your code going to know? Perhaps you have the stepper controller in 1/16 microstepping mode?
"Can't get it to work" is obvious. You would not be here if it worked. What does your code actually do?
The motor seems to rotate continuously in one direction, regardless of whether moveSteps is set as 200 or 3200. Further, setMaxVelocity and setMaxAcceleration doesn't seem to work as I'd expect. Setting the velocity to 3200, with a high acceleration (e.g. 20000) doesn't turn the spindle one revolution per second.
Your calculations look correct. the motor has 200 steps per revolution as you mention, which is why you get 3200 microsteps per revolution when using 1/16th microstepping setting.
The reason you can’t get it to work is because you assume that “moveSteps()” does not return before the steps are made. this is not the case.
Therefore you have to wait for the uStepper to finish the movement before starting the next. the code below should do what you want:
#include <uStepper.h>
uStepper stepper;
uint8_t state = 0;
void setup() {
// put your setup code here, to run once:
stepper.setup();
Serial.begin(115200);
}
void loop() {
// put your main code here, to run repeatedly:
if(!stepper.getMotorState())
{
switch(state)
{
case 0:
stepper.setMaxVelocity(0.37037);
stepper.moveSteps(10667, CCW, HARD);
state = 1;
break;
case 1:
stepper.setMaxVelocity(0.74074);
stepper.moveSteps(21334, CW, HARD);
state = 2;
break;
case 2:
stepper.setMaxVelocity(0.37037);
stepper.moveSteps(10667, CCW, HARD);
state = 0;
break;
}
}
}
You declared a variable with the name "delay". That does not make a delay.
If you just want to delay 10 milliseconds then use the delay() function.
If you have a longer delay, make it a state. Record millis() when you started that state and check millis() and any other inputs while you are in that state.
Thanks again Morgan and Thomas. I've got the delay to work and I can now see what I was doing wrong. Also, my very first attempt was:
case 2:
stepper.delay(1000);
state = 0;
break;
and that created an exit error. I realise now that's because it's an Arduino function, not a stepper function. Just thought I'd mention that for any other readers learning similar tasks.
Currently I'm wondering what safeguards I can add to prevent the motor attempting to run the carriage past the end brackets, e.g. in the event of a power cut resetting the script with the carriage in the wrong place.
I'm looking into:
case 0:
stepper.setMaxVelocity(3200);
stepper.moveToEnd(CCW);
state = 1;
break;
instead of using moveSteps().
Do either of you have any comments on that? I plan on testing it in the lab tomorrow, but feedback would be appreciated beforehand just in case it won't work!
It is called “homing” the stepper. Make one step or a small number of steps, then check the home switch. Repeas as many times as necessary. Usually homing is done relatively slowly.
I did not look at the library to see what moveToEnd() does.
