I have an AR3 built about a year ago. I noticed a lot of nosiy readings from the encoders. After I jog the robot around for a while, the control software will show 'inconsistent encoder value error' and the encoder values drift slightly from time to time. Could this be a shielding problem? I am using unshielded CAT6 cables connecting the robot to the control box and the cables inside the control box are also unshielded. Thanks.
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The external power supply on the AR3 is just to power the 8 channel relay board. I wanted the controller to have the ability to control multiple relays but I dont think many people are using more than one or two relays so in the AR4 drawings I only show the installation of one relay and a nano board. That being said I would not power the encoders from the 5v supply and only from the teensy and do not have the teensy share a common ground with the other board or power supply. I hope this helps and let me know if you have any other questions.
I also found out that the Arduino and Teensy share a common ground since both are connected to the PC. Could this be an issue? I think according to the manual these two microcontrollers should NOT share a common ground.
To follow up, it seems the above only happens when I use a 5V external power supply (which is needed to control servos). If I power the encoder and limit switches with teensy +5V, everything works fine when stepper motors are enabled; If I power a servo with external +5V and common ground to teensy, the encoder values keep increasing. Does anyone use an external +5V power supply for servos? Do you get good encoder readings? Thanks.