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Topic: inter-arduino communication (Read 910 times) previous topic - next topic

harry

Hi all, First post on the forum but been using it for info for a while. Brilliant!

Anyway, i'm starting to develop a simple home automation system. so far i've started to look at how i'm gonna send messages to the slave arduino's from the master. So obviously i'm gonna need addressing, and a protocol of some sort. this is what i've got so far, using the messenger library.

Quote


// This example sets all the values of the digital pins with a list through a callback function

#include <Messenger.h>
// Instantiate Messenger object with the default separator (the space character)
Messenger message = Messenger();
int LEDpin = 13;
// Create the callback function
void messageReady() {
   int i = 0;
   int tempstr = 0;
   int startBit = 9;
   int userInput[2];
      // Loop through all the available elements of the message
      while ( message.available() ) {
     for(i = 0; i<3; i++) {
           userInput = message.readInt();
}
       if (userInput[0] == startBit) {
         
         switch (userInput[1]) {
           case 1:
               Serial.print("One");
                 Serial.print(userInput[2]);
                 if(userInput[2] <2) {
                     digitalWrite(LEDpin,userInput[2]);
                 }
               break;
           case 2:
               Serial.print("two");
               Serial.print(userInput[2]);
               break;
           default:
               Serial.print("Not Understood");
         }
       }
       else {
           Serial.print("NACK");
       }
     }
}
       
       
       


void setup() {
 // Initiate Serial Communication
 Serial.begin(115200);
 // Attach the callback function to the Messenger
 message.attach(messageReady);
}


void loop() {
 // The following line is the most effective way of using Serial and Messenger's callback
 while ( Serial.available() )  message.process(Serial.read () );
}




What do you think? basically i send a "9" as a start bit, then it looks at the next bit to decide where the message is destined, i.e arduino 1 or 2. Then it looks at the last valule to decide what to do. adding another bit on the end could allow for more flexibility. Anyway, is there a better way to do this that using switch/case?

Any info or help will be very gratefully recieved!!!

Harry

Intosia

I suggest using hex values for start bits and so on. Like 0xF0 (use the hex of a wierd ascii character u never use). Hex works faster in computer world. And easier to work with.

harry

ok thanks, how do i send a hex code? is it just a case of sending:

Serial.print(0xFF);

or do i need to do something else?

KyleK

both 9 and 0xFF are 1 byte of data so I don't agree that one is faster than the other. I do agree with the rest of what Intosia said.

int startBit=9;

Serial.print(startBit,BYTE);

Serial.print(0xFF,BYTE);

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