Hi Stefan. The EBB uses some very simple math to determine the time between steps, based on the number of steps in the SM command, and the amount of time that you ask the move to take. There are some higher steps speeds (like you’ve found) that cause this math to ‘break’ and give incorrect results (i.e. motors go crazy). Because the EBB never needs speeds this high, the existing firmware is just fine for normal EggBot use. But you’re in a special situation!
I am currently working on an updated EBB firmware that will solve some other long-standing problems (none that affect EggBot usage) and add some new features (like being able to handle very long moves). I will also now add to my list of things to do your request – to be able to handle faster step speeds. If the EBB is not able to produce smooth steps, it should report back an error (i.e. not say “OK”) rather than making the motors act crazy.
Now, this same type of problem may be happening because your input voltage is not high enough for the motors you are using and your current adjustment pot is set too high. So, can you try this for me? Run your motors over and over at the higher step speeds, and very carefully adjust the current adjustment pot slowly in both directions and see if you can get smoother movement than you’re getting now. You can also try using higher input voltages to the EBB which will help produce more torque at higher speeds.
Let us know what you find, and I’ll get to work on improving the firmware.
*Brian
