Technology Forum Has Moved!

The FIRST Tech Challenge Technology forum has moved to a new location! Please take a look at our forum blog for links and instructions on how to access the new forum.

The official blog of the FIRST Tech Challenge - a STEM robotics programs for students grades 7-12.

Note that volunteers (except for FTA/WTA/CSA will still access their role specific forum through this site. The blog also outlines how to access the volunteer forums.
See more
See less

Update on USB Disconnect Issues (unable to detect USB modules during scan)

  • Filter
  • Time
  • Show
Clear All
new posts

  • I'm seeing total USB scan failures with the new REV Robotics expansion hub. Details, while experimenting with the hub, two motors, a servo and two sensors just wired up and sitting on a table top:

    Adding servo support. HiTEC HS-485HB servo initializes (moves to 0.5 position). Then another USB scan failure. Restart both phones: USB scan good. Servo initialized, then another USB scan failure. Made different servo initialization method.
    Servo stopped working. Try another: nope. Try another port, with change of configuration file: nope. Try the external servo sample: nope. Position report changes, but no actual servo motion. Back to port 0, with change of configuration file: nope. The motor test runs.
    Run the servo sample with no servo: no voltage on any port 0 pin, or any other servo port pin. Battery and +5V pins correct. Swap hubs, rewrite configuration file: nope. Motor test runs. No voltage on any of swapped-in hub servo pins.


    • Hi jrasor,

      If you would please write into our support email [email protected] we'd love to look into this issue with you.

      Rachel from REV


      • Thanks, Rachel! I'll write to your support people.
        Meanwhile, some info from today's logcat. Support will get this.

        1:07 re-deploy, run again to completion. Log says

        Time PID TID prior tag message

        ================================================== ==============

        13:06:35.249 6469 6639 V LynxPwmOutputController: initializeHardware() mod#=2
        ... skipped tons of blather about battery checking and garbage collection ...
        13:06:35.259 6469 6639 W RobotCore: LynxSetPWMEnableCommand not implemented by lynx hw; ignoring. It tried 4 times to do this and LynxSetPWMConfigureCommand. That is definitely no good; servo needs pulse width modulation.