Problem with if else control structure: else condition always performed

Projects Programming
1

Hi! As an exercise I wrote this code to control 8 leds interfacing with a 74HC595 with the Serial port.
The program is really easy: it allows the user to write on the serial a number from 0 to 7 or 'x'. If the input is one of the numbers, it turns on the corresponding led. If the input is 'x', it turns out all the leds.

I also wanted to add an error message in case the input is different, and here come the troubles.
Here's the code in the loop():

byte leds = 0; // define leds status byte
void loop() 
{
  if (Serial.available()){// if there are some data to be sent
    char ch = Serial.read(); // read them as a char
    if (ch >= '0' && ch <= '7'){ // if the char is from 0 to 7
      int led = ch - '0'; // evaluate the led to be turned on
      bitSet(leds, led); // turn to one the corrispong bit in the 'leds' byte
      updateShiftRegister(); // function that saves the byte 'leds' in the 74HC595 register
      Serial.print("Turned on LED "); // communicate to user
      Serial.println(led);
    } 
    else if (ch == 'x'){ // if char is 'x'
      // turn all the leds off
      leds = 0;
      updateShiftRegister();
      Serial.println("Cleared");
    } 
    else { // SOMETHING NOT WORKING HERE 
      Serial.println("ERROR: You have to enter a LED Number 0 to 7 or 'x' to clear");
    }
  }
}

Indeed, it looks like Arduino always executes the instruction in the else condition. Here's what I get from the serial in three different cases:

  • If I insert '0':
    [/code]
    Turned on LED 0
    ERROR: You have to enter a LED Number 0 to 7 or 'x' to clear
    [/code]

  • If I insert 'x':
    [/code]
    Cleared
    ERROR: You have to enter a LED Number 0 to 7 or 'x' to clear
    [/code]

  • If I enter '9'
    [/code]
    ERROR: You have to enter a LED Number 0 to 7 or 'x' to clear
    ERROR: You have to enter a LED Number 0 to 7 or 'x' to clear
    [/code]

Can somebody help me?

2

And what does your code do when you receive a carriage return or linefeed?

Regards,
Ray L.