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I2C Error Code....

Discussion in 'Electronics' started by Chris Daidone, Apr 13, 2014.

  1. Chris Daidone

    Chris Daidone Member

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    While waiting for the new GPS to arrive, I've been systematically trying to enure that the GPS is the actual problem. I had gotten new ribbon cables in from QC yesterday, and I figured I'd try that out first. It seems like its working so far. I have no communication failures and the OSD registers 9 SATs while sitting here in my garage. I dunno... go figure.

    While in MKTools I now notice I have an I2C error 9 displayed in the side (vertical) diagnostic window, second from the bottom. However I do not get this error until I arm the gyros. So I"m guessing it has to do something with the FC board? I already tried reloading the FC firmware... Still have the issue. I've checked all connections on the FC board, and everything seems ok. FC Board light is green and so are all the BL lights. This is my first experience with this. Can someone shed some light on what I need to do to mitigate this?
     
  2. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    By "arm the gyros" do you mean calibrating the gyros, Chris?
    Do you see an increasing I2C error count or just an initial non-zero value? (If it's just an initial non-zero value, that's normal. If it's increasing, that's a problem.)

    All the MK boards are daisy-chained together to form the I2C bus -- so the small white cables with micro-Molex connectors and the six-conductor ribbon cable form the I2C bus -- so it could be any of the cables or connectors that are contributing to a problem on the I2C bus.

    Andy.
     
  3. Chris Daidone

    Chris Daidone Member

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    Yes sorry I meant calibrating. Yeah, it stays the same each time I try calibrating. It goes from 0 to 9.... Once again, thanks for the insight!!
     
  4. Dave King

    Dave King Well-Known Member

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    Chris with the older 2.0 Cinestar 8 power board I had the I2C errors when i initially powered up but they never increased during flight. I flew for 18 months this way never an issue.
     
  5. Chris Daidone

    Chris Daidone Member

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    Thanks a lot for the input Dave. I'm just now getting a handle on all the in's and out's of MKTools and how these boards work. That gives me a bit more confidence as we have our first real gig with this thing next month and I want to make sure without a doubt that things are running properly.
     
  6. Dave King

    Dave King Well-Known Member

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    I would be more concerned about it if you were using the 3.0 electronics. As long as your I2C errors don't go up in number during a flight your ok.
     
  7. Chris Daidone

    Chris Daidone Member

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    And hypothetically if / when they do... What should I start looking at first?
     
  8. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    There's no saying what to look at first, I'm afraid Chris....it's a case of checking all of the wires that make up the bus.
    I also had one of those small six-wire/micro-Molex connectors go bad and, in flight, the whole copter would spasm -- couldn't figure out what it was until I noticed that the elapse flight time kept resenting to zero! Then I had to systematically replace one cable after another until the spasms stopped.

    Andy.
     
  9. Dave King

    Dave King Well-Known Member

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    Chris it could be a cable issue as Andy said or it can be a BL issue. If you narrow it down to the power board itself you will want to do a full visual inspeciton of the board. It's very very easy to get a very small spec of solder or flux splatter on any of the components while you are soldering the board up. What I do after I am done soldering is to take a very very soft tooth brush, tip it isophrol alcohol and very lightly scrub the components on the board. I can't emphasis enough that this must be done extremely lightly because the surface mount components can become dislodged. I do this in combination of an inspeciton with a magnifying glass with a power light.
     
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  10. Sebastian Meredith

    Sebastian Meredith Active Member

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    Chris, as with Dave, we had some I2C errors that fixed on a number at startup and stay throughout the flight. Flew like that for a few months with no issues. On several occasions I went through all the solders on the C&D connectors on the PDB trying to figure out where the problem could be. I even purchased a high power magnifier with LEDS to see if there were any bits of stray solder etc on the BL's. We've just converted out flat 8 to an X8 and in the process I discovered the molex cable connecting the FC to the PDB had one of the wires loose, but not loose enough to drop out. Never noticed this on previous checks. I did not have a spare molex cable so I decided to bypass the molex and hardwire the FC to the PCB. Problem solved. No more I2C errors. Perhaps check the cable and give each wire on the cable a little tug, on both ends.
     
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  11. Chris Daidone

    Chris Daidone Member

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    Thanks Sebastian!
     
  12. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Sebastian: I would be concerned that pulling on each wire might inadvertently create a problem where none existed before. If you happen to have a voltmeter with the capability of testing for continuity, you may find that would be better to disconnect the on Molex connector from both boards and "buzz" each wire. The problem is that the connectors of very small and so you may have to hokey up an arrangement using to dressmakers pins that you connect up to leads of the continuity checker.

    But, as you say, the best way to go, is to solder wires directly to the FC and NC boards. As these only require two wires you can use a two conductor JST male and female connector so that you can disconnect if you need to remove either the FC or NC boards.

    Andy
     
  13. Sebastian Meredith

    Sebastian Meredith Active Member

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    You're right Andy ... a jiggle rather than a tug is what I had in mind. I used a voltmeter initially to do a test but it all tested fine ... I too was concerned that a tug would create a problem that was not there as I've had the molex on the GPX to Nav slip a wire from its housing while removing it during a maintenance session.

    I was getting a different I2C error every time I started up, so all I can think is that the loose wire was still (mostly) making connection and during the startup vibrations it was causing the sporadic error in connection. After eliminating all other obvious problems I finally resorted to hardwiring the FC. When the I2C error cleared I braved a test tug and found the culprit.

    Anyone know how to hardwire and eliminate the GPS molex? hate those little buggers now! :mad:
     
  14. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I don't think there are any pads on the GPS board for the I2C bus, Sebastian, so I suspect you may have to live with the Molex connector.

    Andy.
     
  15. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Waittaminit.....there are four pads next to the Ublox GPS chip, T, 5V, R, and G.
    Transmit, 5volts, Receive and Ground.
    Let me check double check the schematics for the GPS board....

    Stay tooned..
     
  16. Sebastian Meredith

    Sebastian Meredith Active Member

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    Shot Andy ... I can't beat them all .. I'll let that one remained joined!
     
  17. Sebastian Meredith

    Sebastian Meredith Active Member

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    Ooooh! Sorry ... I was too quick on the reply on the last post!!
    Sounds promising ... I'm glued to this channel for breaking news!
     
  18. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hmm. Nope -- sorry. The GPS board does not use the I2C bus -- it connects using serial data lines to the Navigational Control Board, so, although it looks like it's using the same physical micro-Molex connector and wires, the electrical signals that are sent between the NC and the GPS board are different.

    It looks like the only way to connect the GPS board to the NC board appears to be using the existing cable micro-Molex cable.

    Andy.
     
  19. Sebastian Meredith

    Sebastian Meredith Active Member

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    Much appreciated for the quick investigating Andy. Pity, would have been great to bin the molex.
    Cheers!
     

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