I have an Arduino Mega 2560 with a GPS shield on it (Ublox Neo-6M based) and I am using the UBX nav.pvt message (more efficient/faster)... Everything is fine, except of course a mega is large and a shield is much bigger than I need - it's fine for prototyping and SW development.

I have a Teensy 3.2 and a standalone Neo-6M GPS and I was trying to get them working last night (They are the production parts so was testing they all actually work together before designing the PCB). The GPS unit was detected, NMEA sentences were spit out just fine. Great I thought, now I'll load my full program and clean it up so it works on the Teensy.

3 hours later...

Doesn't work... Seems like the GPS chip won't take the command to enable one specific UBX message (It does disable the NMEA just fine, and change the rate to 5Hz)... Stumped.

Reduce program to just bridging serial and the GPS so I can run U-centre (Ublox GPS management app) and sure enough, some of the commands simply don't work - they come back as not recognised. So I got to the extent of manually wiring up the damn shield from the mega to the Teensy (only needed power, gnd, RX,TX) and guess what? Perfect.

So this damn counterfeit GPS works fine in default modes, and supports SOME of the extended commands, but not all - and not the one I need.

I wish it just didn't work at all - I'll never get that time back :-(

Now to try and find a small unit that uses a legit chip. Ugh.

Just had to vent - that's one of the oddest failure/counterfeit manifestations I have seen.

Cheers - N