bookmaker32
USA
Asked
— Edited
Hi guys, Here I am back in bewilderment land. I am trying to run a stepper motor with a Spark Fun Big Easy stepper motor driver. No problem except no matter what PWM I put in the motor runs at the same speed. About 24 RPM. I checked the PWM and it is doing exactly what the EZ-Bv4 tells it to do but the Big Easy just runs the motor at the same speed. Anybody know what is going on?
@Bookmaker32.... Curious... Why a stepper motor?.... Surely a servo is much easier to use...? Are you using it for robot drive wheels?
@Jeremie, I am using all inputs mentioned. I could change the MS1, 2 and 3 for speed but I prefer not to. In addition the most I am getting out of the fastest setting is only about 24 RPM so going slower really isn't what I want to do. @Richard R, I want to use steppers for a few different reasons. You are absolutely correct in that a servo or even a dc motor are much easier to use. I have been there and done that and have some ideas that I want to make happen. I have been building for several months in anticipation of the arrival of my v4 and I am way to far into it at this point to fail. I know I can run them with script and four ports if I must but using a driver seems the way to go.
On this thread I do mention a way to use an L298 H-bridge to control a stepper motor, but it would use the EZ-B to drive the "steps" so it would take up processing power to do it. Its another option but not a very efficient one I admit. I can't be certain but I do suspect you could drive a stepper pretty fast with this method.
@bookmaker32 have you had a chance to try PWMing both the Enable and STEP lines on the big easy driver?
Bookmaker no matter what you do you will not be happy with stepper motors. I went through this and ended up changing my whole design. In order to get it to work you will need to write a piece of code (very easy) like Jeremie has mentioned. No matter what I did to the code, (I ended up removing all sleep commands) the stepper motor just did not perform as expected. I never did find a board that accepts PWM to run a stepper motor driver board, also known as a chopper drive. It also seems there are many ideas of what PWM actually is. Good Luck in whichever direction you go.
I have managed to get my stepper questions answered by experimentation. I made a pulse generator from a 555 timer and I am using that rather than PWM. It works great. For speed control on the Big Easy I am using the M1 M2 and M3 stepper modes. All being controlled by my EZ-Bv4. I did have to add a switch as I did with Buster in his case H-bridges and in this case the Big Easy Stepper Driver, to keep the motors from running when you turn on the EZ-B prior to connecting to the WiFi. In my case I used a TTL solenoid rather than a transistor just because I had one. I used a toggle switch on Buster. If anyone needs help with steppers let me know. I have many hours invested now and feel fairly knowledgeable.
I haven't used one of these myself, but I bookmarked the page for future reference when I ran across it.
Radio Controlled Stepper Kit
It appears to be a Stepper controller that can be driven by an RC radio rig. Of course it could also work with the EZ-B in a robot which is why I bookmarked it.
I am not sure of this but I remember that DJ said sometime, somewhere that the PWM output from the EZ-B is not exactly the same as the PWM output of an RC. That being said I went with a true pulse generator which solved my issue using the EZ-B. Please correct me if I am wrong.
Bookmaker Im glad you found something that worked for you. No matter what method I tried I just couldn't get the speed I was looking for.