[SOLVED] ZED-F9P SimpleRTK2B + Pixhawk 2.1

Dear ArduPilot Family,

I have recently purchased the SimpleRTK2B:

I want to use it as a stand-alone gps “not rtk” and so far I have had no success In connecting it to the Pixhawk 2.1 using Mission Planner. I have tried using both firmwares Rover 3.5.2 and also Rover 4.0.0 with no luck. I have wired up the SimpleRTK2B & Pixhawk 2.1 as follows:

Wiring Method 1 Using JST GH:

SimpleRTKB2 Pixhawk 2.1 GPS2

1: 5V_IN 1 :VCC_5v
2: ZED-F9P UART1 RX. 2:TX of AP
3: ZED-F9P UART1 TX 3:RX of AP
4: Not connected 4:Not Connected
5: Not connected. 5:Not connected
6: GND 6: GND

As you can see the TX & RX on the SimpleRTK2B are different on pins 2 & 3 compared to the Pixhawk. I have tried connecting It like this and have also swapped the TX & RX Pins from the SimpleRTK2B to match the Pixhawk but neither wiring setups work.
Please Note that when done like this the SimpleRTK2B receives No Power.

Wiring method 2 using Micro USB from SimpleRTK2B to Pixhawk 2.1 GPS 2:

I cut a micro usb wire and hooked it up from the USB GPS on the SimpleRTK2B and wired it up to the Pixhawk 2.1 GPS 2 Port.
The micro usb wire has 4 wires;
Red - 5v
Green Rx
White Tx
Black GND

I have connected these 4 wires into the Pixhawk GPS2 Port accordingly and even swapped the TX & RX wires around just in case I got them wrong.
Using this method made the SimpleRTK2B light up and receive power which is a good sign. Unfortunately even with getting power from this method I still cannot get the Pixhawk 2.1 to receive gps data from the module.

Also to mention I have connected the SimpleRTK2B directly into my pc via the Micro USB cable and it runs perfectly in U-Centre & picks up many satellites so it’s working just fine on its own but not when connected to the Pixhawk 2.1

If anyone can help me out I would appreciate any advice. Thank you in advance.

Best Regards,


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You should see something using the JST connector as it should have the correct logic levels for a UART connection.
Have you verified the data rates (baud, parity, etc) between U-Centre and the Pixhawk are the same.
You haven’t mentioned setting any serial port parameters.

Another suggestion is to power the GPS independently instead of from the Pixhawk.
It’s not essential but these days the less your dragging out of the Pixhawk the better, it’s just becoming good practise.


Hi Mike and thanks for your reply.
After hours of trial and error I have finally managed to get the module working on the Pixhawk.

I keep getting Bad AHRS notifications in the HUD for some reason and I am not sure wether I should use AHRS_GPS_USE to be enabled or disabled.

AHRS_GPS_USE: AHRS use GPS for navigation

Note: This parameter is for advanced users

This controls whether to use dead-reckoning or GPS based navigation. If set to 0 then the GPS won’t be used for navigation, and only dead reckoning will be used. A value of zero should never be used for normal flight. Currently this affects only the DCM-based AHRS: the EKF uses GPS whenever it is available.


This is an off topic question. I have been using the Here 2 gps module for a long time.
What I like about it is the LED status lights that blink red & white & then to green when it has a successful gps position lock.

Now I will be using the SimpleRTK2B for GPS which unfortunately doesn’t have LED status on the Antenna like the Here 2 so is it possible to keep the Here 2 solely for Status LED functionality and disable the gps from working?

Would this be done by simply changing parameters or would I need to wire the Here 2 gps LED wires somewhere into the Pixhawk 2.1 to just get LED’s working?

Here’s a picture of the Here 2 but the Pixhawk shown is an older model as I’m using Pixhawk 2.1 Cube:

Yes, you can have both.
To retain all the functionality of leads and button and compass with no GPS just remove the wires on pins 2 and 3.
Everything else should work fine and your SimpleRTK2B just hooks into the GPS port.

You might want to rethink your powering of the devices so as not to drag too much current from the Pixhawk. Those LED’s always worry me being driven directly from the Pixhawk.


could you share info how did you managed to make pikshawk and rtk2b working together? what is you settings in u-center and in pikshawk? and how is your wiring done? thanks in advance.

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@ArduNoob please tell us how did you achieve, it would be good for future users

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Hi can you please elaborate how you got it working thanks

or maybe some one else