DIYDrones Magnetometer issue resolution



It's a long story that I will try to summarize. The latest revision of the magnetometer that had some design improvements including making it easier to manufacture to boost production using the pick and place machine, but that also came with a weird issue. 

When I was developing the APM Oilpan we had some noise issues on the 3.3V line caused by a missing 200K resistor on the Voltage Reference pin on the 5V side of the I2C translator (obviously this board never saw the light), if you don't populate this resistor it will introduce terrible noise on the line and cause the analog sensors to fail, this bug was found by Jose Julio (Thanks!). 


A curious thing is that the first version of the magnetometer didn't have this resistor (it worked fine anyway), in the second revision i tried to do the right thing and follow what the datasheet suggested so I added the 200K resistor (same that caused terrible issues on the Oilpan because we didn't use it), expecting some improvement. 


When the boards arrived from the fab, we assemble some and they appeared to be fine, Cindy (our testing lady) added the observation that the sensors were slightly noisier, but we didn't listen (Sorry Cindy!). For the pressure of months of long waits we just released the boards. In just matter of days we received tons of complains.   


After days trying to solve the problem we finally discover that the 200K was the issue. The 2nd issue we have discovered but is not critical is that the voltage regulator will not perform well if you don't suck enough current from it, the magnetometer uses very, very low power and the best practice to solve this is to add a 200 ohms resistor from the 3.3V to GND to add enough load to it (Thanks to Nathan Siedle for this trick), we are not doing this right now, so you will see a power supply output of 3.7V, but the performance is perfect. 


All new boards have this fix, but for those who already got affected boards I would like to give a sincere apology to all our custumers and I would like to offer two resolutions to this problem:

1.- Send it back and we will repair it for you. We will cover all the shipping expenses. Please contact custumer support for more info: help[@] 


2.-Repair it yourself (DIY) quickly and safely by following the following instructions.


NOTE: Before you repair your board, check if your board has a resistor marked "204". This means it has not been fixed (see the first two photos of the repair steps for reference), and if you see instead a resistor marked "0" your board is fine.

If you choose to repair it yourself and something gets messed up, you cannot then return the board. If you are unwilling to take this risk or are feeling a little uncertain about your soldering ability, do not do this. Just return the board for replacement.























1- Locate the 200k resistor, it is marked with "204."























2- With a soldering iron, heat either of the resistor's solder points
and wait a few seconds for the heat to reach both solder points. Weak solder irons may not work very well. 
























3- Without applying too much force as no not damage the pads, gently
nudge the resistor with the tip of the soldering iron. 
























4-The resistor

should stick to the tip, so just lift the tip off the board to remove
the resistor.























5- Make sure you the pad are still there. 























6- To create the solder bridge place the tip of the soldering iron
over both pads and apply enough solder to brigde the pads.
















































7- If the solder ball is touching both pads then your are done. 


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  • Irie,

    I have a SEN-10530 and tried to connect it by the DIY Drones I2C/SMBus Voltage Traslator (I2C Level Shifter).

    As soon as I connect the magnetometer, the USB connection crashes. After rebooting APM I cant get a mavlink connection.

    Do I have to open the solder bridges on the translator to make it work?

    THX and C U in the Sky

  • I received at the end of March a HMC5843 - Triple Axis Magnetometer Rev 1.2


    I didn't check to see if it was already with this revision before soldering it to the IMU. I've taken one flight with it and what I saw was it occasionally correcting itself but during the correction it would move 10°± and the movement wasn't coming from yaw drift. It seemed like it was over correcting the yaw. 


    I got the magnetometer from diydrones store in US. Would it need to have this solder removed? I just don't want to desolder it to check if I don't have to :) If it has this revision then what would cause this YAW over correcting?

  • my V2 was also configured with a solder jumper for 5V. i would think that for safety's sake that these boards would come jumped for 5V so the user would not destroy the board should they initially use it on a 5V aplication. those of us runnin the 3.3V I2C aplications can easily remedy this by changine the solder jumper.


    just an update - I found my 'grain of sand' 100k resistor during a cleanup of my static mat, and soldered it back on the board. now everything works flawlessly with my ArduIMU.




  • I see everywhere there is stated that the magnetometer comes configured for 3.3V operation, but on my (V2.0) board I can't see other than It's configured for 5V operation.

    Is the silkscreen wrong, or are these units now shipped for 5V as default?


  • I popped a 'OIC' component off of my board today... the component between the "X arrow" and Pin 1 of the I2C interface. can anyone tell me what this component is? i know i can easily get a replacement, but it was stuck to the tip of my soldering iron for a few seconds and i'm not sure if it's cooked.


    thank you for your time and help,


  • To anyone still concerned about buying a magnetometer and receiving a defective unit, we are getting better at working the reflow oven and the PCB cutter! only one unit from today's batch required reworking :)
  • I will say that after this fix, the magnetometer is marvelous.  It calibrated more quickly, and totally locked Yaw in GPS Hold on the Arducopter.  I love it.
  • I get my magnetometer the 12January.

    I didn't had time test it before this post , so I did the change today . It was looking quite easy.

    But It seems I failed The module seems to be short circuit now.

    the voltage on the input drop when I connect it to the ARDUPILOT.


    Any one why the same problem , I eard somthing about solder who go into the other components ?


    Thanks Sandra




  • I had a hard time getting solder to "ball up" between the pads and over the resist.  Just wouldn't bridge.


    It was easier to put down a small piece of wire-wrap wire between the two, tack it to both pads, and trim.

  • Can someone explain which type of cap is the large one right now on every photo here it looks different. Which value and which kind is it right now(ceramic, tantal). Because I know there are issues with this one at Sparkfun.




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