ArduPilot is checking, and may erase, what is stored in the u-blox GPS

What ArduPilot says:

• GPS N: Requesting all config (…) pos=N
• GPS N: u-blox resetting to default config
• GPS N: Found unexpected valget key 0x0x… reset required
• GPS N: CFG-VALGET NACK for FLASH, skipping reset check
• GPS N: Deleting all config and resetting
• GPS N: CFG-VALGET NACK for BBR, trying FLASH

GPS_AUTO_CONFIG is 3 (new in 4.7: clear all configuration not set by ArduPilot, u-blox only). Once after each power-on ArduPilot reads everything stored in the receiver's battery-backed memory (BBR), then in its flash. If it finds a stored setting that is not one of its own (“Found unexpected valget key … reset required”), it deletes all stored settings (“Deleting all config and resetting”), restarts the receiver and configures it from scratch. The two NACK lines mean the receiver has no such memory to read, and the check is passed over.

What to do, most likely first

1. GPS_AUTO_CONFIG was set to 3 to clean a receiver that had been configured with u-center or by another autopilot.

   FixLet it finish. Once the receiver is clean, set GPS_AUTO_CONFIG back to 1, so that its memory is not read through at every start.

2. The value 3 came in with a parameter file, and you did not mean it.

   CheckIf a “Deleting all config” line appeared, whatever you had stored in the receiver yourself (a special rate, a base-station setup) is gone.

   FixSet GPS_AUTO_CONFIG to 1 and set the receiver up again if you need those settings.

Parameters to look at