My colleagues and I and our 5th grade students are getting ready to launch a high altitude balloon for the 3rd time, but this is the first time we've programmed an Arduino to measure temperature, pressure, etc. Last year a parent did all of the programming for us. We've started using Jeremy Blum's (@sciguy14) tutorials on YouTube, specifically Tutotrial 1: Getting Acquainted. We're using an Arduino Mega 2560 and writing the sketch on a Mac (OS 10.10.2). We aren't able to get the led to light up, except when it's first plugged in. Our sketch is exactly the same as Jeremy's. Any tips would be appreciated.
