- Building a 3-axis CNC router. - Stepper motors with step/dir motor drivers. - Beagle Bone Black with Necitec CNC cape.
The cape is just some opto-couplers and buffers for voltage level shifting Nothing fancy. I am experiencing motor drifting when the machine should be at rest. Problem description: 1. After loading Machinekit, both signals are at 0 volt. Expected. 2. I enable the motors/drivers in Machinekit. Both signals are still at 0 volt. Expected. 3. I select an axis (X, Y or Z), and use the [+] / [-] jog command in Machinekit to drive the motor. The DIR signal is left at 0V or driven to about 4V depending on which direction I choose. There is also pulses on the STEP signal. The motor move. This far all is good and as expected. *4. After completing the first jog command (+/- does not matter), the DIR signal starts to oscillate between 0V and 4V continuously. **Not expected.* 5. If I use "disable motors" in Machinekit the DIR signal stops oscillating and goes back to 0V. I believe that #4 cause my motor drivers to start moving the motors very slowly. This is probably an error in it self, as the motor should only move on STEP signal. It is likely that other motor drivers does not exhibit this behavior. But still, I do not think the DIR signal should be pulsing this way. So is there some setting or update to the firmware that can fix this? Attached is two images of my measurements with an oscilloscope. The upper signal is STEP and the lower is DIR. The measurements are from the 2nd/3rd jog command to show that the pulsing of the DIR signal begins after a command is completed and is ongoing until the next command. For the 1st jog command after reboot the DIR signal would be at 0V until after the jog command complete. As you can tell the DIR signal is stable at 0V or 4V during the jog command. Pleas note that these measurements was done without anything connected to the outputs/inputs of the cape. But it is the same with the motor drivers connected (no difference). Any ideas on how to correct this would be greatly appreciated. Thanks. -- website: http://www.machinekit.io blog: http://blog.machinekit.io github: https://github.com/machinekit --- You received this message because you are subscribed to the Google Groups "Machinekit" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. Visit this group at https://groups.google.com/group/machinekit. For more options, visit https://groups.google.com/d/optout.
