====== Adafruit Ultimate GPS ======

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An attractive looking unit with some great features however current versions of the module have an altitude limit of 27km. We understand from Adafruit newer versions are on order that have a limit of 40km however these currently aren't on sale. A prototype of this new unit was successfully tested to 38.5km by UKHAS where it worked with no issues. Nothing needs to be set to engage the high altitude mode. 

**PLEASE BE AWARE ANY MODULES YOU PURCHASE FROM ADAFRUIT AT THIS TIME WILL HAVE A LIMIT OF 27KM**


To test if your module has the 40km firmware on it issue the command $PMTK604*6D (or $PMTK605*31) to the module i.e :

mySerial.println("$PMTK604*6D");

The module will respond with its firmware :

$PMTK705,AXN_2.10_3339_2012072601,**5223**,PA6H,1.0*6A\\  
$PMTK705,AXN_2.10_3339_2012060701,**5153**,,1.0*03\\             

5223 = 40km firmware\\  
5153 = 27km firmware\\  

Weight : 7g

External link : [[http://www.adafruit.com/products/746|Adafruit Ultimate GPS Breakout]]

__Possible interresting update__ from Adafruit on **August 2014**:
//As of 8/10/2014 we are shipping with firmware v. 5632 which improves high-altitude calculations and stability. It is equivalent in all other functionality and is a drop-in replacement.
//[...]
//Maximum Altitude for **PA6H**: according to the factory, this module will perform up to 40Km but it is only known-tested up to 32,000 Meters.
//[...]
//We have received reports that it works up to ~32Km altitude (the GPS theoretically does not have a limit until 40Km).
//[...]
//We've received reports from customers that have tested this version of the Ultimate GPS module in a high-altitude balloon, and it kept fix up to ~32km! There is a (theoretical, untested) firmware limit of 40Km. However, we provide no guarantee that it will work in all HAB's.//