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Thread: Servos resetting IDs?

  1. #11
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    Re: Servos resetting IDs?

    I had another reset last night as well. I was testing some code changes and noticed my power was getting extremely low so I turned my PhatomX AX18 off then realized I wanted to keep the legs in their sitting pose so I flipped it on again while I walked it over to the workbench then flipped it off. Once I had it hooked into the computer I noticed servo 5 and 8 were reset to one.

  2. #12

    Re: Servos resetting IDs?

    Maybe the reason I am not seeing this as much now is after I killed one lipo battery I now usually run with a lipo monitor that I think Trossen sold earlier that plugged into a servo like connection and stop and recharge when the battery gets low, but not too low.

    Kurt

  3. #13

    Re: Servos resetting IDs?

    Forgot to mention that I also enabled lipo safety in my code base. The official code base I believes checks battery voltage when the program starts and will not start if below a threshold, but does not check in main loop..

    The code I am running checks in main loop and shuts down... I was having issues with the query for servo voltage, which my ax12 library fixed, and probably.fixed in new official library as well, but I instead now use a voltage divider circuit and an analog to digital conversion instead as it worked and is faster then sending a packet to servo and wait for response.

    Either way hopefully shuts off servos before I screw up another lipo, and/or maybe reset servo Id.

    Kurt

  4. #14
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    Re: Servos resetting IDs?

    Quote Originally Posted by lnxfergy View Post
    I talked to Andrew, and I plan to run a test over the weekend to see if I can force a servo reset under voltage dropout conditions.
    Any updates on the testing to deliberately cause a reset?

    Also curious if anyone has run into this using AX-12+ or AX-18F as they were intended for a nominal voltage of a 9.6V NiMH battery, where the newer AX-12/18A may possibly be using a different voltage regulator with a higher minimum voltage to better accommodate the 11.1V nominal voltage of a LiPo battery. Maybe? Just thinking out loud again.
    Please pardon the pedantry... and the profanity... and the convoluted speech pattern...
    "You have failed me, Brain!"
    bleh
    more bleh

  5. Re: Servos resetting IDs?

    If anyone is still dealing with the intermitent servo ID reset, I have had very good results by replaceing the code in the servo driver.
    It has been several week since the last reset and I used to see them several times a day when working on the bot.

    replace

    for (byte i = 0; i < NUMSERVOS; i++) {
    Relax(pgm_read_byte(&cPinTable[i]));
    }

    with

    Relax(254);

    Maybe this week ill scope it out and see if there is somthing happening on the bus when a server is de-energized that would explain what is happening.
    Cheers

  6. #16
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    Re: Servos resetting IDs?

    Any new developments on this front? I think i just had my first case of AX12 ID resetting. I'll confirm with the mentioned debug tool soon.

  7. #17
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    Re: Servos resetting IDs?

    I'm fairly positive this is low-power/brownout related.

    I can tell you that with our various (numerous) crawlers we have around the shop, we run lipo monitors on everything and shut them off as soon as they get low and we've not seen a servo reset in over a year.

  8. #18
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    Re: Servos resetting IDs?

    That could be what's at play here too.

    The ONE time i ran my bot without the lipo monitor, i was showing a friend for maybe 2 minutes tops. The bot started to act weird so i stuck on the lipo monitor and it was down to 7.8V! so i powered off and threw the battery on the charger. Fortunately it charged up fine. Then a few days passed until yesterday.

    Yesterday i was back to my usual debugging, etc on the bench. I noticed that everything was normal except one servo was not behaving. The lipo monitor was plugged in and all voltages good. I then programmed it back to "stock" code and it was still not behaving. Then it degenerated and other legs began to go nuts. After each power cycle it would either flip out or legs would stay limp, just random. The whole time the lipo monitor read 11.8V. I checked the servo voltage with a multimeter and confirmed. I checked the 5V to the Arbotix and it was 4.97V.

    Running on FTDI power, Kurt's AX12_Test program loads up on the serial monitor. It doesn't react to any of my inputs, though, maybe because the servos are not powered in this configuration? I would like to see a message of some sort at least though.

    Running on lipo power with the FTDI programming connected as my serial interface, Kurt's utility either doesn't run or it displays half the test with some of it garbled up. Lipo voltage still looked ok.

    So I think i can attritibute the one servo going nuts as its losing its ID due to low voltage. I'm not sure what all this other mess is. I need to find a 12V power supply to run the bot without the battery for benchtop work.

    After work today i'll get my lipo fully balance charged. I ordered a charger balance cable extension that will make it easier for my to balance charge with the battery in the bot. I had only balance charged when i first got the kit. I've charged it three times now unbalanced. Then I'll try to run Kurt's test program again.

    Also: Will Kurt's AX12_TEST allow me to reprogram the servo IDs? It looks like so, but i'm not sure if my hardware setup will work. Will it program over my serial interface created using the xbee FTDI programmer? If not i'll have to order the USB2Dynamixel
    Last edited by TXBDan; 05-29-2013 at 08:57 AM.

  9. #19

    Re: Servos resetting IDs?

    Yes, my program does allow you to reprogram the Servo, BUT: you need to unplug the real servo with id #1 before you reprogram #1 to whatever the servo that changed should be, otherwise it will also get reprogrammed. If it on the same chain as #1, you can always play games of reprogram real #1 to some unused, then reprogram the bad one to the right number and then change the one that is supposed to be #1 back to 1

    Kurt

  10. #20
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    Re: Servos resetting IDs?

    Kurt, I'm having trouble interacting with your AX12_Test program.

    My connections:
    Stock built MarkII Hex, Arbotix -> 6 wire header jumper -> XBee Explorer (FTDI) -> USB Cable -> PC This is my programming and serial link
    Fully charged lipo, power switch on. Arbotix power jumper set to VIN. Lipo is powering the servos and Arbotix

    I can Compile and Upload your code no problem. I can open the Serial Monitor and i see the LEDs on the Arbotix start to flash and then on the serial terminal i see System voltage. It strangely reports 65535 which i don't understand.

    I see your main menu, 0-9.

    But when i enter a number and press the Send button, nothing happens. I see in the code that not all commands will give me print feedback to the terminal, but at least command 9 should, right? I'm seeing nothing. I tried Autoscroll checked and not checked.

    Any ideas?

    As another strange issue, i can also flash the stock Nuke MarkII code and the legs stay limp. Even with the Commander and Xbees connected. They just stay limp. Actually i just tried this code using the FTDI serial link and i can see the voltage check at startup print out. It reports my servo ID1 voltage to be -0.10 volts. I can measure it with a multimeter and it is 12.2V. So that explains why the legs stay limp, but i wonder why the reading is wrong. :/

    When i flash my code (which has no communication checking before activation) the legs fire up into their starting positions fine except for the one femur servo is acting just like Servo ID1 who i suspected got reset.

    Any help would be much appreciated. Thanks!
    Last edited by TXBDan; 05-29-2013 at 05:16 PM.

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