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Moto E4 Phones Disconnecting

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  • #16
    Originally posted by Cheer4FTC View Post
    but if I comment out the 2 telemetry lines, it disconnects after 30-60 seconds. So this does seem to point towards some timeout issue in the Moto E4 driver station if it doesn't get any messages for a while
    Sorry, I edited my last post badly...

    I was asking if you could send a Driver Station log file showing the disconnect.

    It's probably doing it all the time when app is sitting idle, but you just don't notice it until you init the opmode.

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    • #17
      Huh... if it is a screen inactivity timeout, can you check to see if the sleep timer is set to a really short time eg: 1 min.
      If so, can you extend the sleep time out, and test again.

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      • #18
        We checked the sleep timer and it is set at 30 mins but we lose connection between 30 and 45 seconds. Is FIRST still working on this?

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        • #19
          Tom Eng has there been an update?

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          • #20
            thensley The workaround is to add a telemetry message during init_loop (or while waiting after init in a LinearOpMode). This seems to prevent it from disconnecting.
            CHEER4FTC website and facebook online FTC resources.
            Providing support for FTC Teams in the Charlottesville, VA area and beyond.

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            • #21
              We were using "while !isStarted()" but not sending any telemetry back to the phone so we replaced the while !isStarted() with "
              while (!opModeIsActive()&&!isStopRequested()) { telemetry.addData("Status", "Waiting in Init"); telemetry.update(); }" and it seems to be working fine. Thanks for the help guys! Cheer4FTC

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              • #22
                Thank you everyone for the feedback and troubleshooting. This specific issue was not revealed when we tested the phones this past summer. The workaround appears to be sending telemetry messages while waiting for a start command.

                I've updated the Troubleshooting section of the GitHub ftc_app Wiki to include details on how to avoid this problem for Blocks and Java programmers:

                https://github.com/ftctechnh/ftc_app...eported-102018

                Tom
                Last edited by Tom Eng; 11-26-2018, 09:38 AM.

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                • #23
                  Hi Folks - Note that this problem is not limited to the Motorola E4 phone. The same behavior occurs for the Moto G5 and G5 Plus phones. If these phones are used as a Driver Station and are in the waitForStart state for a period of time (which has been observed in as little as 30 seconds, or as long as 3 minutes) the Driver Station phone can disconnect momentarily from the Robot Controller.

                  The workaround prescribed for the E4 phone also works for the G5 or G5 Plus phones.

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                  • #24
                    Originally posted by Tom Eng View Post
                    ... The workaround prescribed for the E4 phone also works for the G5 or G5 Plus phones.
                    Thanks Tom. Does this mean you heave tested and approved the Moto G5 Plus phone, i.e. it is now legal?

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                    • #25
                      Originally posted by Tom Eng View Post
                      Thanks all for the detailed info. We'll check this out. I wonder if this is some type of power save issue (just thinking out loud - I do not have any evidence that it is).
                      I think that's actually a very good hunch. My guess is that the radio is idling because of the low bandwidth usage. I've actually seen evidence of this on our Nexus 5s - when sitting idle the ping is ~25ms, but if I start moving around the analog sticks, it immediately drops to ~3ms

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                      • #26
                        Hi Folks - just some additional info...

                        I believe the G5 Plus phone is very similar to the G5 phone, except it has a larger screen and a metal backing. Regarding the status of using a G5 phone, I think the best place to ask the question is on the Q&A forum. I am unable to rule on its legality for use in FTC.

                        We have reached out to some contacts and have brought this issue to the attention of Motorola. I'll update the forum when we learn more about the issue.

                        Tom

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                        • #27
                          Originally posted by Tom Eng View Post
                          ... Regarding the status of using a G5 Plus, I think the best place to ask the question is on the Q&A forum. I am unable to rule on its legality for use in FTC...
                          A phone cannot be legal unless the Tech Team has tested it. Your previous posts suggest that the Tech Team has tested the Moto G5 Plus. Please confirm that the Tech Team has tested this variant of the G5 so that we can have a basis for seeking a ruling from the Q&A forum.

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                          • #28
                            Originally posted by Alec View Post

                            A phone cannot be legal unless the Tech Team has tested it. Your previous posts suggest that the Tech Team has tested the Moto G5 Plus. Please confirm that the Tech Team has tested this variant of the G5 so that we can have a basis for seeking a ruling from the Q&A forum.
                            Hi Alec,

                            Yes we have tested the G5 Plus phone.

                            Tom

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                            • #29
                              Thanks Tom, I will go ahead and seek a ruling on the legality of the Moto G5 Plus. Did you mean to say "If these phones are used as a Robot Controller" instead of "Driver Station":

                              Originally posted by Tom Eng View Post
                              Hi Folks - Note that this problem is not limited to the Motorola E4 phone. The same behavior occurs for the Moto G5 and G5 Plus phones. If these phones are used as a Driver Station...

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                              • #30
                                Hi Alec,

                                The problem happens when the newer phones are used as a Driver Station (G5, G5 Plus, E4, E5). We think we know what the problem is caused by. The Motorola phones can scan the wireless spectrum (to detect what wireless resources are in the vicinity). We believe that when the system is in the WaitForStart mode, the Driver Station phone might decide to scan the spectrum if there is relatively low wireless activity happening.

                                For the older Motorola phones (G4 Play, G 2nd gen and G 3rd gen) this scan completed in a short amount of time since the phone only scans the 2.4GHz channels. With the newer phones (E4, E5, G5, and G5 Plus), the scan physically takes more time because it also scans the 5GHz (non DFS) channels.This longer scan can cause the safety timeout mechanism of the FTC software to kick in (the wireless radio is being used by the scan process so it's not available for the FTC Driver Station app to send heartbeat messages to the Robot Controller).

                                Sending the telemetry messages from the RC to the DS while waiting for the start seems to suppress this scan mechanism.

                                We are working with some contacts at Motorola to try and find the optimal solution to our problem. For now, the workaround described in the link below is the best recommended course of action.

                                https://github.com/ftctechnh/ftc_app...eported-102018

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