# RM3100 Magnetometer

Source: https://forum.modalai.com/topic/684/rm3100-magnetometer
Category: Flight Core and Legacy VOXL (https://forum.modalai.com/category/9/flight-core-and-legacy-voxl)
Tags: voxl-flight
Posted: 2022-01-26 23:40:22 UTC by m4v3r
Replies: 5 · Views: 1621

## m4v3r · 2022-01-26 23:40:22 UTC

Hi ModalAI, ^^

I'm encountering issues with a certain compass on your flight controller.
I detailed the issue here [link text](https://discuss.px4.io/t/rm3100-on-modalai-fc-v1-px4-1-12-3/25934?u=christian-born) 
but in general I wonder, do you guys have any specific experience with this mag unit?

I'll try and keep you updated. Thanks for your work, guys!

## Reply by modaltb (ModalAI staff) · 2022-01-27 17:45:49 UTC

Hi @m4v3r ,

I'm nearly positive I tested CONNECTIVITY on the "drotek" version of this with success (I mainly remember that I did fry one out of two by reversing GND and VDD...).

I'll try to find this when back in the office and give it a go and report back.

## Reply by m4v3r · 2022-02-07 19:52:17 UTC (in reply to modaltb)

@modaltb Hello there, I just wanted to give a little update here:
I managed to connect it in a way that it's now appearing on the I2C bus as 23 by putting a 10k resistor on vcc and the I2C-enable pin but it's still not being detected by PX4 as a magnetometer and I couldn't start it manually either.
I do see it on the bus just like with another mag ("gy-85" board using the QMC5883L and two other IMUs which also appear on the bus when scanned) but can't get it to start and work in PX4.

## Reply by m4v3r · 2022-04-02 14:07:44 UTC

Hey, just giving some more information and a little bump since I'm still in desperate need of this compass working on my drone.
Please try and have another look into this for me if you could... ;)
thanks so much and a perfect weekend for everyone.
cheers

unit on bus:
![mag-1.jpg](https://forum.modalai.com/assets/uploads/files/1648908438907-mag-1.jpg) 

Tried starting it manually to no avail:
![mag-2.jpg](https://forum.modalai.com/assets/uploads/files/1648908462426-mag-2.jpg)

## Reply by modaltb (ModalAI staff) · 2022-04-06 15:44:18 UTC

@m4v3r , sorry for the lag.  This mag is not in our office.  What I would do myself is go into the driver and see what's happening.  We don't re-sell this mag and I don't have one so I'm stuck a bit.  Do you want to ship one to us and we put a debugger on PX4 and see what's up?

## Reply by m4v3r · 2023-01-27 00:32:36 UTC (in reply to modaltb)

@modaltb Hey hey know it's been forever but just right now I finally got it working. :)
I adjusted the adress in the corresponding driver's .h file and now it's finally running. 
thanks again for going through this with me.
cheers