Arduino will reset when you open the COM port. You probably send the 'Hey' while Arduino is resetting. Give Arduino time to reset. You can add a pause to Matlab or do the following:
Try adding the following in Arduino:
above void setup()
char a = 'b';
in void setup()
Serial.println('a'); // send the char 'a' to the serial port followed by carriage return character (ASCII 13 or \r) and newline character (ASCII 10 or \n)
while (a != 'a') // while a does not equal 'a'
{
a = Serial.read(); // read the first available byte from the serial port and store as a
}
And in Matlab after you open the COM port add the following:
a='b';
while (a ~='a') % wait until you receive an 'a' from Arduino
a=fread(s,1,'uchar');
end
fprintf(s,'%c','a'); % send an 'a' back to Arduino
