Dealing with Hex

Projects Programming
6

Here is how to do it with a union.

union ctrlUnion
{
  long ctrlLong;
  byte ctrlBytes[4];
};

ctrlUnion ctrl;

void setup() 
{
  ctrl.ctrlLong = 0xffeda976;
  Serial.begin(115200);
  Serial.print("long version ");
  Serial.println(ctrl.ctrlLong, HEX);
  for(int n = 0; n < 4; n++)
  {
    Serial.print("byte ");
    Serial.print(n);
    Serial.print(" = ");
    Serial.println(ctrl.ctrlBytes[n], HEX);
  }
}

void loop()
{
}

Then send the 4 bytes in the order required.