This is for a Arduino Nano based Barometer and temperature sensor that outputs NMEA 0183 over USB so it can be read in Open CPN.
It's based on work originally done by Ingmar using a BMP180. You can read about this here: https://sdfjkl.org/blog/2017-08-09-nanobaro/
This version was creeated for another user during this thread: http://www.ybw.com/forums/showthread.php?484828-Nanobaro-NMEA-USB-barometric-sensor-easy-DIY-electronics-project
I offer no warranties or any guarantees that this is fit for any purpose whatsoever, but feel free to use it!