Microstepping with L6208

[mt2]

Posted on May 19, 2009 at 08:45

Microstepping with L6208

[mt2]

Posted on May 17, 2011 at 10:15

Hello,

I have developed a two axis microstepping driver with two L6208. I have found some problems to drive it correctly in CW/CCW (CCW request a different sequence) but now it work fine with high resolution (> 50000 steps/revolution). But I have a problem when I change the state of DIR signal from CW to CCW or reverse, every time that I change this signal the motor do a little step (I have an encoder as feedback). This is true only when I work in fast decay mode while L6208 don't show this problem when I work in slow decay mode. I use L6208 in NORMAL mode (1,3,5,7) and with full step signal enabled, the current range from 0.5 to 2A. Probably I don't generate correctly some signals but I really don't understand this behaviour. Is possible to have a logic diagram of the digital block? Thank you very much for any help. Regards Manuele

[enrico-dora-spa]

Posted on May 17, 2011 at 10:15

Hello Manuele,

Unfortunatly, it is not possible to have the logic diagram of L6208 state machine. However CW/CCW signal do not have a direct effect on full-bridges driving logic. Have you checked the toff and voltage reference stability? Can you post some oscilloscope waveforms that shows the issue? Regards, Enrico Poli Application Engineer - Motor control group

[Fedele Tagarelli]

Posted on July 19, 2017 at 15:19

Hello,

I am trying to implement microstepping on a X-NUCLEO-IHM05A1, which i am using with an Arduino uno. I have followed the microstepping application note, and i obtained the right waveforms at l6208 references' input pins. Here you can see the waveforms obtained with my oscilloscope. Of couse the sinusoidal waveforms have been probed at the onboard low pass filter's output. 1 and 2 are respectively the waveforms for refA and refB, while 3 is the Clock signal fed to the shield.

At setup i have also implemented the initialization routine, which briefly is Reset, then apply 5V to both refs, than apply PWM with 0.7 DC on both refs.

At the end the stepper doesn't rotate in a single direction, but rather oscillates between two position with a swing of several steps, probably 5 or 6.Do you have any clue or hint of what could cause this behaviour? I thought about the power supply, and the one i am using is a standard wall plug one with output 12V and 1.5A, which seems to work smoothly with another board based on L298 and same stepper motor, so i don't really think this is problem. But i have tried also with a bench PS unit and with higher voltage (say 20V and 4A) and the stepper could rotate but not steadily and very noisily. Thanks for the help.Regards, Fedele.