Getting Two Arduinos to Communicate Through Serial

Projects Programming
1

Hi - I've done a lot of digging regarding this topic, but any links pertinent to my situation would be greatly appreciated.

So I'm working on a project with two Arduino 101s that requires them to communicate to each other through Serial connections - one takes data from the user and sends it to the other, which sends back a response to the first that is printed to the Serial Monitor.

Unfortunately, I've been having no luck even getting the Arduinos to recognize one another, much less send anything through Serial.

I came across this earlier today, which I figured would be a great proof-of-concept:

  • but I can't get this to run either, so I believe the issue lies in how the Arduinos are connected/how I upload the sketches.

I've connected the two at the TX/RX ports (TX to RX and vice versa), their GND and their 5V power source, essentially as in this video:

If someone could give me a step-by-step as to how to upload the code from the stackexchange link in order to make it run successfully, that would be great.

EDIT: To clarify, there is probably some problem with my connection/upload process to the two Arduinos. So here it is:

  • start with 2 fully disconnected arduinos
  • connect the receiver Arduino to USB
  • upload the "server side" code from the link above
  • disconnect the USB cable
  • connect the two Arduinos together (RX/TX, GND, 5V)
  • connect the sender Arduino to USB
  • upload the "sender side" code from the link above

And nothing happens.

  • connect the two Arduinos
1 Like
2

I use the 3rd example in Serial Input Basics for communication between my Arduinos.

You can send data in a compatible format with code like this

Serial.print('<'); // start marker
Serial.print(value1);
Serial.print(','); // comma separator
Serial.print(value2);
Serial.println('>'); // end marker

...R

3

Thanks for your help - I actually found your post earlier while crawling the web for solutions. And while it will definitely come in handy when it comes time to create my program, the issue I'm having is not with code so much as connectivity. In other words, I don't think that the two Arduinos I'm using are actually transmitting any data to each other.

4

ogsc1524:
the issue I'm having is not with code so much as connectivity.

Make a simple pencil drawing showing how you have things connected and post a photo of the drawing. See this Simple Image Guide

Have you a GND connection between the two Arduinos?

...R

5

Here's a quick sketch. Location of pins/connections has been changed for clarity's sake.
Also sorry about the mess with the RX/TX cables but one goes to the other.

quicksketch_1.jpg
quicksketch_1.jpg2048×2730 817 KB

6

ogsc1524:
Thanks for your help - I actually found your post earlier while crawling the web for solutions. And while it will definitely come in handy when it comes time to create my program, the issue I'm having is not with code so much as connectivity. In other words, I don't think that the two Arduinos I'm using are actually transmitting any data to each other.

IF you are not using a program that transmits data and another program that receives and prints the data, just what are you using that gives you the idea that they are not communicating?

Paul