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No more encoder positions for Neverest and tetrix motors.

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  • No more encoder positions for Neverest and tetrix motors.

    Suddenly I'm not getting any motor currentposition values other than 1.0 for Tetrix and Neverest motors, but the same exact code for CoreHex motors works. (I'm using the REV expansion hub.)
    I stripped down a test bench to test. I tried different ports on the expansion hub. Tried different motors and cables. I thought it might be the 1.7.2 firmware so I fell back to 1.7.0 and 1.6.0. No difference in behavior. I call stopandresetencoder, runwithencoder, power=0.3, then loop using telemetry with current position. Am I forgetting something? Is anyone else having a similar problem? I recently switched from ZTE to Moto G Play phones. Could that be it? HELP! Gary Lindner, Coyote Robotics, FTC 3749.

  • #2
    The Tetrix and Neverrest motors produce a different voltage than the REV motors. They require a level shifter when connected to a REV Expansion Hub. See https://youtu.be/U3E5AM56xzg

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    • #3
      I've been using the level shifters. I have had encoders working for these motors since October. Now they don't work. I tried a new TorquNADO tetrix motor and that encoder worked. Tried several other original tetrix and neverest motors and they don't work. I'm going to try my old ZTE phones next.

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      • #4
        Tried again with Moto G Play DS to ZTE RC as well as ZTE to ZTE. Problem persists. Torquenado and Core Hex work. Tetrix and Neverest display only 0.0, 1.0, 2.0, occasionally changing. Attached is printout of code.
        Attached Files

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        • #5
          The code shown in your PDF looks fine. Have you tried moving the level shifter currently cabled to your Torquenado motor to one of the other motors to see if the symptom moves? You might also try changing the order that the motors and encoders are plugged into your REV and adjusting the Config file to match to see if the symptom moves.

          Also, the RUN_USING_ENCODER mode together with the power setting of 0.3 that you are using should cause all four motors to run at 30% of their individual maximum speeds based on the brand/model you have specified in the config file. If the speed control is working, that is an indication that the encoders are working well enough for motor controller built into the REV. If you are not seeing consistent speed control under varying load for some of the motors, that would be an indication that REV is not receiving the encoder signal for those motors.

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          • #6
            It does sound like a level shifter issue.

            When you say it was working fine, and then it just stopped, my mind asks: Did you do any rewiring at that same time? eg: Moved to new hardware, cleaned up the wiring layout? Mounted the level shifters in a new location that required unplugging and re-plugging?

            Something as simple as an unexpected plug reversal could cause all your current issues.

            Phil.

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            • #7
              Thanks for your help. I think I've tried everything the both of you mentioned but have not documented my process. I will start again and test all the possible configurations.
              Phil, It worked before on two different robots but they have been completely disassembled. We have built our new design and were beginning to test and program with temporary wiring.
              I'll keep at it. Thanks again. Gary

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              • #8
                Hi All,

                I think we are going through this exact problem on one of our robots. The encoders on motors that worked fine last year don't work this year. They are Neverest 20 using level shifters with the Rev Hub.

                Plug in the Torquenado encoders and everything works fine.

                Did you have any tips? Thanks.

                Chris

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                • #9
                  We had something similar and found out that via the adapter, we wired the encoder motor cable to the rev Hub wrongly. I will try to check tonight the correct wiring connections and post it.

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                  • #10
                    Thank you. I borrowed an oscilloscope and determine that we have two cables that have the same connectors. One of the cables doesn't not have the correct pin-out between the level shifter and encoder. Using the correct cable should fix it. We didn't have a chance to test the software yet, but I am confident the cable was the problems.

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