[FTC]: Tetrix motor controller weirdness with 4 motors

[Scott_4140]

4 motors on one controller worked fine for us with the new motors at our first Qualifier.

Don't confuse FRC and FTC. There is nothing in the FTC rules preventing 4 motors on one controller.

Also, from the LEGO Education site:

http://www.legoeducation.us/eng/prod...or_tetrix/1648

The HiTechnic DC Motor Controller for TETRIX® connects to an NXT Intelligent Brick sensor port and will enable you to control powerful DC gear motors for use with TETRIX robots. The controller has two H-bridge outputs to control the speed and direction of two DC gear motors and is designed to connect to the TETRIX hole pattern. A four-motor robot can also be built by paralleling two motors to one channel. A total of four DC Motor Controllers for TETRIX and/or Servo Controllers for TETRIX can be daisy-chained to provide additional motor and/or servo outputs on each port.

--Scott

[aklego]

Originally Posted by Scott_4140

4 motors on one controller worked fine for us with the new motors at our first Qualifier.

...

This is good to know although I'll admit that I was hoping other teams w/a similar setup could reproduce the problem.

We have our qualifier this weekend that we'll run with our current setup and then return to troubleshooting after the event.

Lots of suggestions of an over-current fault but that seems inconsistent with the applied load. When we return to troubleshooting I'll instrument the controller and see what our current actually is.

[Al Skierkiewicz]

ak,
I received some info that the I2C passes through the controller in the event of a fault. So if you are having issues down stream from a particular controller, that device could have an issue or you could have a defective cable. However, there is still the off chance that one of the drive motors has excessive friction causing some high motor currents. You need to isolate the motors and see if you can find that issue as well. You mentioned in your first post that the motors are mechanically coupled, so it is possible that one of the motor issues is being coupled into the other. If you remove one electrically the mechanical problem still exists. Good luck this weekend.