Home › Evil Mad Scientist Forums › Egg-Bot › 400 steps / revolution steppermotors higher speeds than 1000 steps per second › Re: 400 steps / revolution steppermotors higher speeds than 1000 steps per second
March 15, 2014 at 6:26 pm #21780
I just did some testing with EBB v2.0.1 firmware. I have no problem running my motors at step rates up to 32,000 steps/s.
I have some 400s/rev steppers that I’m using for testing (like your setup). Since we have 16x microstepping, this should provide me with 1 full revolution at 6400 steps. So I executed the command:
I saw my motor move exactly 1 revolution in exactly 1 second (timed with a logic analyzer on the step signal to the motor driver chip). This proved that we are able to handle step speeds up to 6400 steps/second no problem. The motor moved very smoothly.
Since the largest step value you can use with SM (in this version of firmware) is 32,767, I decided to pick a nice round number of 32,000 steps. I then did
And saw exactly 5 rotations (as expected). However, the timing is off – the total move took around 1.4 seconds, and the pulses to the motor driver were not equi-spaced in time. The way that the EBB generates pulses, each pulse has to line up on a 25KHz ISR boundary, so the fastest step rate we’ll ever see is 25,000 steps/second out of the EBB. Since I’m asking it to do 32,000 steps/second, it still took the exact right number of steps, but it had to spread them out a bit and thus take longer than 1 second.
Again, my motors smoothly moved the 5 revolutions. Even thought the pulses sent to the motor driver were not perfectly smooth, the mechanical system of the motor smooths them out and we get smooth motion.
So, in answer to your question: can the EBB support step speeds above 1000 steps/second? Yes, absolutely it can, as these experiments show. Up to about 25,000 steps/second, things should work as you expect.
My guess, at this point, as the the cause of your issues is a mis-adjusted current adjustment pot on the EBB. It appears that the firmware is doing what we expect of it.