Mission Planner "GPS: No GPS" with Holybro Micro M8N GPS

Tattu 6S 14,000mAh Lipo
Pixhawk 2.4.8
6 Spedix IS45 Dshot Bheli_S 45A ESC’s
6 T-Motor MN4012 KV400 Motors
Flysky FS-i6 Transmitter
Flysky IA10B Receiver

I am working on a hexacopter build for a school project (specs listed above). I have downloaded Mission Planner 1.3.68 build 1.3.7105.26478 and have followed the steps on there to install Arducopter V3.6.11 onto my Pixhawk. I was able to do all the initial calibrations with the accelerometer, compass, and radio.

However, Mission Planner states GPS: No GPS. I have a Holybro Micro M8n GPS module installed. I had to splice the 6 pin cable from the GPS unit into a 6 pin connector plugged into the Pixhawk GPS port, and a 4 pin connector plugged into the Pixhawk I2C port. I currently have the following connections:
GPS Connector:
Holybro GPS GND ------> Pixhawk GPS Pin 6 (GND)
Holybro GPS TXD ------> Pixhawk GPS Pin 2 (TX out)
Holybro GPS RXD ------> Pixhawk GPS Pin 3 (RX in)
Holybro GPS 5V -------> Pixhawk GPS Pin 1 (VCC)

I2C Connector:
Holybro GPS SDA ------> Pixhawk I2C Pin 3 (SDA)
Holybro GPS SCL -------> Pixhawk I2C Pin 2 (SCL)

The Pixhawk’s light if flashing yellow and apparently it should be flashing blue if the GPS is searching for satellites. The Holybro Micro GPS has a solid green light and a flashing blue light.

From what I have searched, the GPS should work automatically without enabling it with any settings. Is this correct? Can anyone help me resolve this issue? Thank you.

Try swapping the TX/RX pins


The Holybro is a capable little GPS and I have logged a lot of flights with them. Agree with @Implicit - swap the Tx/Rx pins.

That was the trick! Thank you for your help. I swapped the RX and TX pins and the GPS now works for the first time. Its odd that the stated pinouts for the GPS and the Pixhawk do not function.

They do function… TX is for transmitting, RX is for receiving. So a TX Pin has to go to an RX Pin

yeah, RX goes to TX, vice versa…and then sometimes, they try to be helpful and label where RX should go, so you do it wrong anyway.

1 Like

I’m having a similar issue: GPS: No GPS but I am using a Spektrum Dx8 radio with my receiver plugged into the dsm/spkt port on Pixhawk 4.2.8
I am using a Ublox M8N GPS/Compass unit.
I have no idea if I’m doing something wrong or if the Pixhawk/GPS are not working correctly. I have no way to test it.
Otherwise the system seems to be working OK. When I pick up the drone the Heads up Display updates accordingly.

Try to swap TX and RX connections as @Implicit did suggest. Also you have to set Parameter SERIAL3_PROTOCOL=5 for Ublox.

Where do I make that swap?

in the cable connecting GPS to Pixhawk

I don’t see any way to do that. There are 2 plugs, one seems to be a data plug and the other is power.

Can you post a picture how are plugs look like and where are they plugged in?

This will give an idea how to swap the Rx & Tx wires.

It could be unnecessary in @JMal3’s case.


    December 23

It could be unnecessary in @JMal3’s case.

Visit Topic or reply to this email to respond.

In Reply To


      [Hari .P](https://discuss.ardupilot.org/u/ambattuhari)

    December 23

This will give an idea how to swap the Rx & Tx wires.

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Thats enlightening! I will give that a try. The connector on the gps unit I haven now is a 5 pin connector and the socket is a 6 pin socket. I had not looked at it that closely before, since I assumed that what I was getting was compatible with the Pixhawk I have.
I will have to try to find a 6 pin plug.
Thank you!

Some sellers ship the module with an extra 6pin connector. If you havn’t thrown away the packaging, look for it.:slightly_smiling_face:

At least you didn’t cause any damage because the way you jammed the 5 pin connector in left the +5V pin open.

BTW- Your comment about the system otherwise working OK because the HUD is moving is not definitive. The HUD will move with no GPS or compass connected at all from the Z-axis gyro. If upon boot the HUD shows the craft pointing North every time regardless of it’s actual heading then the compass is not working.

I found a 6 socket connector and made the changes as per the video you linked me to and the gps unit lit right up and I am no longer getting the GPS: No GPS warning I was getting before! Yes I’m klutzy as they come but your assistance is greatly appreicated.


Did you start flying the hexa ? I’m wondering if you’re running into overheating ESCs trouble !?