I've been using other microcontrollers in a project which communicate with each other through digital pins. The uCs are too slow, so I need to upgrade to Arduinos. The problem is, I can't find specifics anywhere & I've already apparently blown up one of my Nanos.
First of all, how do I wire them together? Do I pull down to ground on the input, or up to 5v? What size resistor do I use? Do I put a resistor on the output, and what size? Why, when I use resistors, do the other uCs (or the other Arduino) power up with no Vcc hooked up to them?
Second, what is the exact protocol? Data bits, stop bits, parity, and does the line idle high or low?
Third, what do I have to do with the code to get it to work? I've read the SoftwareSerial routines on this site, and nothing has worked yet. Also, the Arduino seems to have some weird logical rules, I've got "If" statements that seem to run all the time, regardless of the condition being tested.
I'm trying to send three-byte data packets from one to the other...