SparkFun RTK Express Hookup Guide
Contributors:
Nate
Nate 
Firmware Updates and Customization
The RTK Express is open source hardware meaning you have total access to the firmware and hardware.
From time to time SparkFun will release new firmware for the RTK product line to add and improve functionality. We've made updating the firmware as easy as possible. Please see Updating RTK Firmware for a step by step tutorial.