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Rev expansion hub disconnects in a no vibration environment

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  • Rev expansion hub disconnects in a no vibration environment

    This is our first year using the Rev Expansion hubs. We have updated them recently to the latest firmware (1.8.2). We are using ZTE speed phones and the lastest 4.0 SDK. My kids are characterizing the Rev 2m laser distance sensor and the V2 color sensor. The only thing they have connected to the hub is one of the sensors, battery and phone. They reported that they are seeing frequent but random disconnects from the hub to the RC phone. I observed and see 4-10 disconnects per hour. I do not believe it is due to the need for strain relief. They can leave the setup perfectly still on a table and still get a disconnect. The connectors are all relatively tight and there is no discernable vibration applied to the table. We do not believe ESD is an issue since they are not touching the setup and still get disconnects. The disconnect is confirmed by a lack of communication with phone and the hub led sequence switching from green-blue blinks-green to blinking blue. Once a disconnect occurs they have to reboot the hub and phone to get a connection re-established. Restarting the RC app does not do it. This has us concerned about the future when we put the system on a robot with it vibration and esd environment, even with strain relief and esd protection. Has anyone experienced this?

  • #2
    We have this problem as well. Frequently when we run an opmode, the rev hub would disconnect, and we can't stop the opmode. The disconnects happens frequently as well. Both apps freeze and display the rev hubs have disconnected when this happens. My team is very concerned with this as well and wonder if there is a solution.

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    • #3
      Are you connecting RC to Hub directly or through USB hub? Also try replacing cable. If you are not using USB hub then I suggest OTG micro to mini cable that way you avoid one usb joint

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      • #4
        Yes the RC is connected to the hub directly. No USB hub. We did swap cables. We have 2 expansion hubs and several phones. We have swapped expansion hubs, phones and cables. Same problem. WE have not tried a OTG cable but will. I'm suspicious this is not a hardware problem. Are there debug logs or steps we can take to get more information to present in this thread?

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        • #5
          Yes, there are logs. You can access them by plugging the phone into the computer and putting it into file transfer mode, or by downloading them from the Program and Manage web interface

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          • #6
            We had similar issue last year but got resolved by factory resetting phone. You might have already tried that but if not see if that helps

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            • #7
              We reset the RC phone, but we still have the same REV Hub disconnects. We are using an OTG cable and the S5's. This disconnect makes it very difficult to test the robot because every other time we run our TeleOp, the REV Hub disconnects and both apps freezes. At this point, we cannot stop the OpMode and the only way to test is to reset the RC App. Does anyone have any other suggestions?

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              • #8
                Did it happen when running autonomous ?

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                • #9
                  I'm back. We have done extensive testing with our setup and we really suspect this is a software problem.
                  Environment:
                  - ZTE Speed running Android 4.4.4
                  - REV expansion hub running firmware 1.8.2
                  - REV color distance sensor V2 on I2C bus 1 (also happens with Laser distance sensor)
                  - Opmode - SDK provided SensorRevColorDistanceSensor.java (with NO modifications)
                  - RC and hub on table with no vibrations or movement

                  result: rev hub will detach anywhere from 10 seconds to 12 minutes after starting opmode

                  Adding an idle() statement at the end of the opmode loop did not change the results.
                  However, commenting out all of the actual I2C calls to the sensor fixes the problem. So it seems like the I2C communication is playing a role in this problem.

                  I'm not sure how to present the log so I put it on google drive here: https://drive.google.com/file/d/1XP4...ew?usp=sharing

                  Any ideas? Please?

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                  • #10
                    We also noticed that the SDK provided opmode was not efficient in that it requested multiple I2C transactions to get the same information. We re-wrote the opmode so that only one call was made to get distance, red, blue and green. This did not fix the problem.

                    We are concerned because we plan on using I2C sensors heavily and suspect other teams will too.

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                    • #11
                      If other teams can run this simple test I would be grateful to hear the results:
                      - run either one of these SDK supplied opmodes for 10-15 minutes and report if you disconnect from the rev hub or not. No mods to the opmodes are needed, just setup a config on your phone and go.
                      - FtcRobotController -> java -> org.firstinspires.ftc.robotcontroller -> external.samples -> SensorRevColorDistance or SensorRev2MDistance

                      Let us know what version firmware you have on the hub, the type of phone and the version of java you are running

                      Thanks!

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                      • #12
                        Can you post a copy of your robotControllerLog.txt file from your RC phone?

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                        • #13
                          Tom, check the link in post #9.

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                          • #14
                            We did have disconnect problems last year. It seemed to be a loose connection at the point the cable plugs into the REV Expansion Hub. We added some duct tape to make sure the connection was secure. There are probably better options and yours sounds like it may be a more complicated problem, but it may be worth a shot.

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                            • #15
                              Hi Folks - Thanks for pointing me to the log file. If you look in the log file you can see the following error message:

                              10-29 21:16:08.374 7967 8193 E RobotCore: lynx xmit lock: #### abandoning lock: old=LynxI2cReadStatusQueryCommand(239)
                              10-29 21:16:08.374 7967 8193 E RobotCore: lynx xmit lock: new=LynxKeepAliveCommand(0)

                              This message seems to suggest that a bug in v 4.0 (and also in v4.1) was causing the disconnect. The development team believes that this bug has been addressed with release v4.2 of the software. Details on the software release can be found here:

                              https://github.com/ftctechnh/ftc_app...se-information

                              If you can install the v4.2 software and retest, hopefully you will have better results. Our testing suggests that the fix in v4.2 addresses this problem of the deadlock which causes the disconnect.

                              Tom

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