Getting Redboard + sparkfun Weather Shield readings to Photon [SOLVED]

[ScruffR]

There are several threads in this forum that could get you started
Search results for 'arduino photon' - Particle

Most of them get stuck at some point, that's why the posted here, but the solutions should be there too.

But if this doesn't get you anywhere, we're here to help

This seems to be a good one, although the level shifting should not be required for the Photon as the RX/TX pins are 5V tolerant.

Spark (3.3v) to Arduino (5v) Serial Communication

This is in reference to another thread, but I got a Spark talking via serial to my Arduino Uno using a logic level converter (I actually used one from eBay, but it works the same). The goal of this little test is to see if I could write from the Spark to the Arduino and listen for any serial data that the Arduino might generate. It’s pretty simple and straightforward. Since my test Arduino is an Uno, I’m limited to SoftwareSerial, so I had to scale down the baud rate. I will eventually tap t…

There are also some things that have slightly changed since 2014, but the general idea is in the code.