Understanding the ESP-NOW code

Posted by: @awpologies

 

  if (esp_now_add_peer (&peerInfo) != ESP_OK) {
    Serial.println("Failed to add peer");
    return;
  }  

 

Now I'm having some questions about what this piece of code actually does:

1. In the first line of code, are we killing two birds with one stone here? Are we calling a function named esp_now_add_peer with an earlier declared variable named peerInfo, so it will add a peer, and then immediately check if it does not return with ESP_OK?

Yes

1. Where does the function esp_now_add_peer come from? Is it there because I included a header a header file called esp_now.h? If so, is there a way to look inside esp_now.h to see what other functions are available?

Yes, look for the documentation or, if desperate, look at the .h file itself. It will be in the general directory chain of

your home > Documents > Arduino >libraries > folder with library name > library name.h

DO  NOT   MODIFY  ANYTHING  IN THERE !!!!

1. Why is there an "&" in front of peerInfo? I understand it has to do something with the location of peerInfo in memory. Why do we need it here?

Because you're passing the address in to the function. Depending on the context which you haven't shown, this is likely so that the call can change the value at that address and thus return the peer info to you.

1. Why do we type return; at the end of the if-then statement? What is this piece of code actually returning? Or are we just telling the compiler to return to the rest of the code?

Because if the creation failed, then this subroutine or function cannot proceed any further so it returns control back to whatever called it.

@will 

That helps a lot, thanks for answering! 

Now I can go break my head over an other piece of code 😉

Cheers!

@awpologies Actually you did pretty good on your own, but master @will did his usual expert polishing. You have NOOOOO idea how refreshing and rewarding it is to see your question and response to the help provided. Keep it up.