inter-arduino communication

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.

// 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 () );*
    }
    [/quote]
    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

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.

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?

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);