This is a small project to display new mail notification with a RGB LED connected to an Arduino.
Every few minutes, the computer will check a Gmail inbox for unread emails. If one or more unread emails are found, it will tell the Arduino to turn a light on.

Electrical Diagram:

Bash Script:

On the computer, a bash script is running to regularly check for unread emails on a Gmail account. Depending on the result, a number will be send to the Arduino in order to display a notification.

• 0: No new mail.
• 1: Red LED, error while fetching the number of unread mail.
• 2: Green Led, new emails.
• 3: Blue Led, new emails.

#!/bin/bash
#SCRIPT_NAME="Arduino Gmail Checker"
#SCRIPT_VERSION="0.1"
#figlet $SCRIPT_NAME $SCRIPT_VERSION
#########################################################################################
# Description: Check Gmail for unread email and switch RGB LED on Arduino in accordance #
# Dependencies: sed, curl,                                                              #
# Author: Virtualmix                                                                    #
# http://blog.trollmaker.com/article10/arduino-led-notification-for-gmail-on-linux      #
# License: CC BY                                                                        #
#########################################################################################
# Enter Gmail username and password below (Warning: Unsafe storage):
USERID=yourUsernameHere
PASSWORD=yourPasswordHere
# Enter number of seconds between email verification:
WAIT=300
#########################################################################################

# Loop to check for new mail every X minutes:
while [ "1" -eq "1" ]; do

    # Command line to fetch the number of unread emails:
    MAILCOUNTER=`curl -u $USERID:$PASSWORD --silent "https://mail.google.com/mail/feed/atom" | sed -n 's|<fullcount>\(.*\)</fullcount>|\1|p'`

    if [[ "$MAILCOUNTER" = "" ]]; then
        echo "ERROR: The program coulndn't fetch the account for user \"$USERID\"."
        echo "- Are you connected to the Internet?"
        echo -e "- Is the userid and password correct for \"$USERID\"?\n"
        echo 111 > /dev/ttyUSB0 # Turn Red Led on
    elif [[ "$MAILCOUNTER" -eq "0" ]]; then
        echo "* There is 0 new email for user $USERID."
        echo 000 > /dev/ttyUSB0 # Turn all leds off
    elif [[ "$MAILCOUNTER" -gt "0" ]]; then
        echo "* There is $MAILCOUNTER new email for user $USERID."
        echo 232 > /dev/ttyUSB0 # Turn blue and then green led on
    fi

    echo "* Waiting $WAIT seconds before checking for emails again."
    echo "* (^C to quit the program)"
    sleep 300

done

Arduino Code:

The program running on the Arduino is very simple. All it does is wait to receive a number sent via serial communication from the computer.

• 0: The LED will is turned off.
• 1: Red LED is switched on.
• 2: Green LED is switched on.
• 3: Blue LED is switched on.

/*****************
RGB LED connected to Arduino with 330 ohm resistor to GND
Read value from serial and set LED high or low depending on the number received
0: All off
1: Red LED on
2: Green LED on
3: Blue LED on
******************/

int redLed = 11;
int greenLed = 10;
int blueLed = 9;

void setup() {
  Serial.begin(9600);
  pinMode(redLed, OUTPUT);
  pinMode(greenLed, OUTPUT);
  pinMode(blueLed, OUTPUT);
}

void loop () {
  int value = Serial.read();

  if (value == '0') {
    digitalWrite(redLed,LOW);
    digitalWrite(greenLed,LOW);
    digitalWrite(blueLed,LOW);
  }

  if (value == '1') {
    digitalWrite(redLed,HIGH);
    digitalWrite(greenLed,LOW);
    digitalWrite(blueLed,LOW);
  }

  if (value == '2') {
    digitalWrite(redLed,LOW);
    digitalWrite(greenLed,HIGH);
    digitalWrite(blueLed,LOW);
  }

  if (value == '3') {
    digitalWrite(redLed,LOW);
    digitalWrite(greenLed,LOW);
    digitalWrite(blueLed,HIGH);
  }

  delay(1000);
}

Download:

Bash Script and Arduino Code:

• arduino_gmail_checker.zip

Let me know if you ever make something cool with it!