[jhm5z588]

I have just purchased a M8N and it only had one plug that was just for the gps but i noticed two wires that were clipped right where the wires come out the insulation, I removed the cover off of the gps and it was the two wires for the SCL and SDL and now I2c is hooked in to the Flexiport and is green along with everything on my screen until i switch to INS13 then Atti, Mag and Stab turn Red but I2C is still Green I2C is the Aux mag correct bc then i go to the Screen that shows Percitages for Internal and external Mags and it says the is no External Mag?

Please Help this could be a stupid mistake and Im sure i am just missing a step but can not find a topic that describes my problem

[jtrout19]

From what I have been reading on here and other forums some of the clones are missing the Compass IC on the board. Have you opened up your unit to see if there is anything missing? I might be totally wrong here cause Im still learning just thought your post has been here for a minute without a reply so i thought I could give you some place to start.

[Mateusz]

Hi,

You could verify by checking if GPS has mag inside. You should set in GCS to use both magnetometers before calibration. Then from what I remember (top of my head) there is another drop-down list with DJI, I2C, Flexi afiak. The DJI is to use GPS uart to extract mag from there if you happen to have DJI GPS (you dont). Then there is I2C port, which you don't have on Revo (exists only on sparky2), and Flexi which is what you want to choose. Then save, reboot, and then perform calibration. Click to last step ignoring instructions, and on last (5th or 6th) step just before finishing calibration, move copter with battery in all directions to cover as much as possible. It is MANDATORY to do that outdoors and using op-link far from metallic objects and not on the ground. Usually people run in trouble ignoring this principle so please do calibrate outdoors. Stuff like "maybe it will work indoors" is just no go. Then when ready with mag calibration, you can set rotations. By default software expects your external Mag to be in the same rotation as Internal one, but this may not be the case as different manufactures put chips wherever they want. So you adjust those rotation axis by multiply of 90 deg, until you see 0,0,0 on bars. Not multiply of 90 makes no sense to me. You get 0,0,0 when both magnetometers rotation matches and since you calibrated them with "Use both" they should give similar read-outs. Now when this is done, you have to set "Use Auxiliary" to use external only.
Another mandatory thing that must not be ignored is that GPS+Mag (actually mag) must be mounted on a mast that is not rotating and far above copter plane. I use 14cm mast that has two screws at the bottom so it will not rotate. My mast also folds backward in case of front crash, but important is it should not rotate as that would invalidate magnetometer calibration.

Finally, Complementary (Basic) sensor fusion algorithm uses just Gyro+Accel. Then you have Complementary+Mag to test mag. And INS13 uses ALL sensors, including baro which also must be properly calibrated. Any of the sensors not working properly makes flying impossible at all or not reliable. GPS itself has 4-6 meters of errors, so it must be combined with other sensors data to improve position estimation.

[jhm5z588]

I Appreciate all of your help one big thing i realize i did very wrong was try the calibration in the house and i know it does have the mag/Compass i have opened it up to make sure the wires were hooked up which they are. Hopefully since i did the calibration inside that is why it says no aux mag on the screen where you select which gps and which mag you would like to use i will try again tonight outside and let you know what happens.

[Mateusz]

I Appreciate all of your help one big thing i realize i did very wrong was try the calibration in the house and i know it does have the mag/Compass i have opened it up to make sure the wires were hooked up which they are. Hopefully since i did the calibration inside that is why it says no aux mag on the screen where you select which gps and which mag you would like to use i will try again tonight outside and let you know what happens.

If you don't connect battery then GPS+Mag is not powered and it will be not found. Batter is needed to be connected.

[jtrout19]

That was an awesome post man. I have to thank you as well as that will help me get setup when my new revo arrives today!!

[jhm5z588]

Has anyone had a problem with a mag falling off the Gps i still was not able to get it to pick up that the mag was there, so i took the cover back off and lying in the housing was the mag. I have no clue which direction it should be soldered back or even if i am capable of soldering something that small any tips for soldering it or what direction it should be? I contacted the seller but no word back yet i have not wrecked not sure if this is a common problem?

[jtrout19]

Gonna have to use a hot air rework gun or an infrared gun. Its not complicated to do in my opinion but i work on electronics daily its my job and all the stuff i do is micro soldering and rework stuff. The issue is gonna be orientation but if you can find someone with the same gps you have and have them take the cover off you will be able to see what orientation to put it

[Mateusz]

Has anyone had a problem with a mag falling off the Gps i still was not able to get it to pick up that the mag was there, so i took the cover back off and lying in the housing was the mag. I have no clue which direction it should be soldered back or even if i am capable of soldering something that small any tips for soldering it or what direction it should be? I contacted the seller but no word back yet i have not wrecked not sure if this is a common problem?

I suggest you read symbols on your Mag which are probably L883 something. That is 16 pin QFN package. This package has small dot or other marking which indicates where first pin is and orientation. Usually on the PCB board should also be marking. If there is no such marking try to figure out obvious routes like I2C or power where it connects to chip, this might give you the clue about what should be the correct orientation if you combine this with datasheet for you magnetometer.

In the datasheet you should have a temperature curves for oven. Since you can't control temperature as in the oven, I suggest you take very small nozzle for hot gun, use twizzers to hold chip down and soldering paste with some flux. Keep chip at correct orientation and use hot-gun to reflow not exciting max temperature and not heating up too rapidly. Be careful not to de-solder remaining components.

This sounds difficult but it's pretty easy. Alternatively just order small magnetometer board connect it to power cables and i2c cables inside gps.
Maybe you can find it cheaper https://www.adafruit.com/product/1746 but something like this could also work I guess.

[jhm5z588]

Ok i have the hot air rework station but do not know of anyone who has this same gps. I just broke down and bought a dji naza gps module. This is my second M8N the first did not have the mag and it was supposed to now i have one with the mag and it falls off M8N and me just dont get along at this point in time. Hopefully i will have less problems with the naza. I have plenty of 4 pin jst connectors so thats the way im going to try to go.

[jhm5z588]

Has anyone had a problem with a mag falling off the Gps i still was not able to get it to pick up that the mag was there, so i took the cover back off and lying in the housing was the mag. I have no clue which direction it should be soldered back or even if i am capable of soldering something that small any tips for soldering it or what direction it should be? I contacted the seller but no word back yet i have not wrecked not sure if this is a common problem?

I suggest you read symbols on your Mag which are probably L883 something. That is 16 pin QFN package. This package has small dot or other marking which indicates where first pin is and orientation. Usually on the PCB board should also be marking. If there is no such marking try to figure out obvious routes like I2C or power where it connects to chip, this might give you the clue about what should be the correct orientation if you combine this with datasheet for you magnetometer.

In the datasheet you should have a temperature curves for oven. Since you can't control temperature as in the oven, I suggest you take very small nozzle for hot gun, use twizzers to hold chip down and soldering paste with some flux. Keep chip at correct orientation and use hot-gun to reflow not exciting max temperature and not heating up too rapidly. Be careful not to de-solder remaining components.

This sounds difficult but it's pretty easy. Alternatively just order small magnetometer board connect it to power cables and i2c cables inside gps.
Maybe you can find it cheaper https://www.adafruit.com/product/1746 but something like this could also work I guess.

Thank you for all your help. I am going to order a mag board for the one of my gps and try to solder the mag back on the other. Have you tried the naza v2 Gps with a revo which would be a better way to go in you opinion?

[Mateusz]

DJI has mag data integrated over serial connection using proprietary protocol which was reverse engineered. That means you need to use just one port on Revo and no need for additional I2C connector. It's better way in my opinion. Also I2C is tricky as some boards don't have strong enough pull up resistors or too long wires affect signal. Better go with DJI one.

[jhm5z588]

DJI has mag data integrated over serial connection using proprietary protocol which was reverse engineered. That means you need to use just one port on Revo and no need for additional I2C connector. It's better way in my opinion. Also I2C is tricky as some boards don't have strong enough pull up resistors or too long wires affect signal. Better go with DJI one.

Ok one last question if i ordered this mag and run it to the flexi port and attach it to the gps the mag should work the same as if it was soldered on the board correct?
http://www.ebay.com/itm/261748761510?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

[Mateusz]

Check symbols on mag you have on Revo if same then it will work for sure. Other hmc5883L might work as well. Should be in the code which are supported but I can't check now from phone. I suggest you check symbols on mags that worked.