A configured GPS has never answered

What ArduPilot says:

• GPS N: was not found

A GPS slot has a type set (GPSn_TYPE not 0), but no receiver has been recognised on it since power-on, so arming is refused. For a serial GPS ArduPilot keeps trying each speed in turn, 4800 to 460800 baud, 1.2 s each. With automatic configuration on (the default) a u-blox module is recognised only at 230400 baud, the speed ArduPilot itself switches it to: the flight controller must be able to talk to the module, not only listen to it.

What to do, most likely first

1. TX and RX are swapped, or only one of the two data wires is connected.

   CheckThe GPS's TX goes to the flight controller's RX, and its RX to the flight controller's TX. A lit LED on the module shows that it has power, nothing more.

   FixCorrect the wiring; the Board & Wiring Planner shows which pads belong to which UART.

2. The serial port the GPS is wired to is not set to GPS.

   CheckThat port's SERIALn_PROTOCOL must be 5. The first serial GPS takes the first port set to 5, a second GPS the second.

   FixSet it to 5 and reboot.

3. A second GPS is configured but not fitted.

   CheckThe message says GPS 2.

   FixSet GPS2_TYPE to 0 and reboot.

4. The type does not match the receiver, or a CAN receiver has no CAN bus to talk on.

   CheckA DroneCAN GPS needs GPS1_TYPE 9 together with CAN_P1_DRIVER 1 and CAN_D1_PROTOCOL 1. A serial u-blox module works with 1 (auto) or 2.

   FixSet the type that matches and reboot.

5. The module is not a u-blox and speaks plain NMEA, which auto-detection does not look for.

   CheckGPS1_TYPE 1 (auto) never selects NMEA.

   FixSet GPS1_TYPE to 5 (NMEA) and reboot. Expect less from such a receiver: ArduPilot cannot set its update rate.

Parameters to look at

Where to do it:Board & Wiring PlannerSetup & Tuning Guide