unsigned char unitNumber = 0xff;

const String asText[] = {
  "B4:E6:2D:8E:50:A1",
  "B4:E6:2D:8E:67:45",
};


uint8_t broadcastAddress[][6] = {
/* 0 */	{0xb4, 0xe6, 0x2d, 0x8e, 0x50, 0xa1},
/* 1 */ {0xb4, 0xe6, 0x2d, 0x8e, 0x67, 0x45},
};
 
void selectUnit()
{
	char asChars[20];

	unitNumber = 0xff; // no it doesn't
	
//	String myMACAddress = WiFi.macAddress();	// if you use this for real...

//	String myMACAddress = "B4:E6:2D:8E:67:45";  // simulated! will succeed

	String myMACAddress = "B4:E7:2D:8E:67:45";  // simulated! will fail


	Serial.print("I am "); Serial.println(myMACAddress);

	if (myMACAddress == asText[0]) unitNumber = 1;
	else if (myMACAddress == asText[1]) unitNumber = 0;

	if (unitNumber == 0xff) {
		Serial.println(" MACAddress assignment fail!");
		for (; ; ); // whatever you want to do when you have no partner. Me, I die.
	}
	else {
		Serial.print("I'll talk to unit "); Serial.print(unitNumber);
		Serial.print(" at "); Serial.println(asText[unitNumber]);
  }	
}

void setup() {
	Serial.begin(9600);
	Serial.println("unit selection test");

	selectUnit();
}

void loop() {}