I have setup a quad using the Matek H743-Slim FC and an M8N GPS module w/ Compass. I successfully get the GPS communicating with the FC. However, the compass is never detected.
I have the GPS/Compass module connected as follows:
GPS Gnd → FC G
GPS VCC → FC 4v5
GPS TXD → FC Rx2
GPS RXD → FC Tx2
GPS SCL → FC CL1
GPS SDA → FC DA1
Since everything I’m seeing indicates the compass should be autodetected, and it should be on the I2C bus, I’m at a loss on what else to do to troubleshoot this issue. Here is a picture of the GPS module in case it helps.
Just for grins, try swapping the CL and DA connection. Maybe something is mislabeled. It is not harmful to do so - worst case, it still won’t communicate.
Thanks for the suggestion. I have connected it both ways, neither of which worked as expected. That’s when I cracked open the GPS module and snapped the picture to verify the wires.
This FC has the 4v5 pad for the GPS. To my knowledge this pad should be powered from the USB when connected to the ground station computer…Mission Planner.
For the record, here are some of the troubleshooting steps I’ve taken so far:
Based on the 4v5 pad, I have tried with the FC just connected to the USB, but have also tried with a flight battery plugged in, minus props of course.
Swapped the SDA / SCL wires connected to the FC.
Looked for Mission Planner parameters that might affect I2C or Compass.
Enabled Compass_External → set to 1 instead of the default 0.
At this point I’m at a loss on what else to check. In another thread regarding someone having issues with autodetecting the compass they mentioned compass chip support. I’m really not sure how to go about verifying if the compass chip on this module is supported or not. Help there would be appreciated if someone is knowledgeable.
By this are you meaning to say verify the continuity of say where the wire is attached to the FC and where the wire is attached on the GPS module?
On thought I had was to verify the SDA / SCL were actually sending data, but have no idea how to go about that.
The GPS module was something I had from a quad I built 5 years ago. I really don’t recall the make, and of course the module is just one of those very generic looking GPS modules on a post. Not sure how to determine make/model at this point.
I have enabled compass 1 via the UI and rebooted, in fact I tried enabling all three compasses via the UI. Should I set this directly in the Full Parameter list instead of just via the UI?
HEY!!! It was the COMPASS_ENABLE param. That worked!!! I was under the impression the UI Use Compass 1 / 2 / 3 were toggling this. I set COMPASS_ENABLE to 1 and it found it. Thanks for the insight.
Hey Jason I am also facing kind of same issue. After you resolved this issue did your Multi color LED glow?. I had a working setup f405 CTR flight controller and M9N GPS module from pixhawk.
It was working but after few day I powered it on with flight battery which was in good shape and all the soldering connections are good. But didn’t turn on the compass it seems. Looks like GPs having a fix but compass was not found
